ACL Restoration using Semitendinosus Tendon

Back to the list of contents   |  List of references

Abstracts

Aglietti P, Buzzi R, D'Andria S, Zachacchererotti G: Patellofemoral problems after anterior cruciate ligament reconstruction. Clin. Orthop. 288; 195-204, 1993.
A series of 226 anterior cruciate ligament (ACL) reconstructions were reviewed to determine the incidence of patellofemoral (PF) problems and the associated prognostic factors. Patients were divided into four groups according to the type of injury (acute or chronic) and operation (through an arthrotomy or arthroscopic assisted). The average follow-up period was 39 months. Overall there was a 5% incidence of PF crepitus with pain and/or swelling, and a further 20% of clear PF crepitus without pain. The change from open surgery and cast to arthroscopic surgery and early motion allowed a decrease of PF problems from 40% to 21% in acute injuries, but the difference was less marked in chronic knees. A deficit greater than 10% at the one leg hop test was present in 75% of the knees with PF crepitus and pain. The height of the patella was increased in 5% and decreased in 17% of the knees. Patients with rehabilitation difficulties had the largest decrease in patella height, whereas a patella alta was more frequent after patellar tendon reconstruction. A significant correlation was found between PF problems and female gender, positive congruence angle, preoperative PF crepitation, rehabilitation difficulties, flexion loss greater than 10 degrees, extension loss greater than 5 degrees, and variation in the height of the patella. The importance of avoiding immobilization, rehabilitation difficulties, and permanent flexion or extension loss is emphasized. (List of references)

Aglietti P, Buzzi R, Zacherotti G, De Biase P: Patellar tendon versus doubled semitendinosus and gracilis tendons for anterior cruciate ligament reconstruction. In: Am J Sports Med (1994 Mar-Apr) 22(2):211-7; discussion 217-8
The results of intraarticular anterior cruciate ligament reconstruction with either the patellar tendon or the semitendinosus and gracilis tendons (four strands) were prospectively compared in a consecutive series of 60 patients with chronic injuries. A single surgeon performed arthroscopically assisted reconstructions in an alternating sequence. Preoperative and operative data revealed no significant differences between the two groups. After 28 months of follow-up there were no significant differences in the incidence of symptoms, and recurrent giving way was present in only one knee with semitendinosus and gracilis tendon graft. Return to sport participation was more frequent in the patellar tendon group (80% versus 43%, P 0.01). A minor extension loss ( or = 3 degrees) was more frequent in the patellar tendon group (47% versus 3%, P 0.001). Other differences between the two groups were not significant. KT-2000 arthrometer side-to-side difference of anterior displacement > 5 mm at 30 pounds was present in 13% of the knees with patellar tendon grafts and in 20% of those with semitendinosus and gracilis; a patellofemoral crepitation developed in 17% and 3% of the two groups, respectively. Based on these data we routinely use patellar tendon grafts. Semitendinosus and gracilis tendons are preferred in selected cases: older patients, patients with pre-existing patellofemoral problems, and those with failed patellar tendon grafts. (List of references)

Black J.: Does corrosion matter? J. Bone Joint Surg., 70-B(4): 517-520, 1988.
To overcome many of the complications after ACL reconstruction (prolonged knee stiffness, limitation of complete extension, delay in strength recovery, anterior knee pain), yet still maintain knee stability, we developed a rehabilitation protocol that emphasizes full knee extension on the first postoperative day and immediate weight-bearing according to the patient's tolerance. Of 800 patients who underwent intraarticular ACL patellar tendon-bone graft reconstruction, performed by the same surgeon, the last 450 patients have followed the accelerated rehabilitation schedule as outlined in the protocol. A longer than 2 year follow-up is recorded for 73 of the patients in the accelerated rehabilitation group. On the 1st postoperative day, we encouraged these patients to walk with full weight-bearing and full knee extension. By the 2nd postoperative week, the patients with a 100 degrees range of motion participated in a guided exercise and strengthening program. By the 4th week, patients were permitted unlimited activities of daily living and were allowed to return to light sports activities as early as the 8th week if the Cybex strength scores of the involved extremity exceeded 70% of the scores of the noninvolved extremity and the patient had completed a sport-specific functional/agility program. The patient database was compiled from frequent clinical examinations, periodic knee questionnaires, and objective information, such as range of motion measurements, KT-1000 values, and Cybex strength scores. A series of graft biopsies obtained at various times have revealed no adverse histologic reaction. The evidence indicates that in this population, the accelerated rehabilitation program has been more effective than our initial program in reducing limitations of motion (particularly knee extension) and loss of strength while maintaining stability and preventing anterior knee pain.
(Back to the list of references)

Cooper D E, Deng X H, Burstein A L, Warren R: The strength of the central third patellar tendon graft. A biomechanical study Am. J. Sports Med., 21: 818-824, 1993.
Thirty-seven bone-patellar tendon-bone composite grafts from the knees of 21 human cadavers were tested to failure. Average donor age was 28 years. The composites were divided into 4 groups: 3 groups with 10 grafts (5 pairs) and 1 group with 7 grafts from 6 donors. In Group 1 we tested 10- versus 15-mm wide grafts that were used without twisting; Group II, 10-mm wide grafts without twisting versus 10-mm wide grafts that were twisted 90 degrees; Group III, 10-mm wide grafts twisted 90 degrees versus 10-mm wide grafts twisted 180 degrees; and Group IV, 10- versus 7-mm wide grafts that were not twisted. The tests were performed using a newly described potting technique and clamp system and a servohydraulic testing machine with an elongation rate of 5 cm/sec. The results of this study suggest that the central third of the patellar tendon is stronger than previously reported. The mean ultimate load of a 15-mm bone-patellar tendon-bone composite was 4389 N (+/-708); of the 10-mm wide composites, 2977 N (+/-516); and of the 7-mm composites, 2238 N (+/-316). Twisting the graft 90 degrees increased the strength (P lesss than 0.05). Further twisting to 180 degrees had no significant effect compared with twisting 90 degrees. This study supports the practice of using smaller (10 mm) bone-patellar tendon-bone grafts to avoid the potential complications of patellar fracture and graft impingement in the notch.
(Back to the list of references)

Cross M J, Kujawa P, Roger G, Anderson I F: Regeneration of the semitendinosus and gracilis tendons following their transection for repair of the anterior cruciate ligament. Am J Sports Med (1992 Mar-Apr) 20(2):221-3.
Apparent regeneration of the tendons of the semitendinosus and gracilis muscles after their use for anterior cruciate ligament reconstruction was noted during routine follow-up of 225 patients. From this group, four patients were selected for thorough examination, including magnetic resonance imaging, electromyographic studies, strength testing, and clinical examination. The results demonstrate that these tendons appear to regrow and are probably functional.
(Back to the list of references)

Dye O: The future of anterior cruciate ligament restoration. Clin. Orthop., 325, 130-139, 1996.
Advancements in the understanding of anatomy, kinematics, and physiology should improve future treatment of anterior cruciate ligament injured knees. The ultimate goal of full restoration of an anterior cruciate ligament injured knee to preinjury status, may be possible in the distant future through genetic manipulation inducing regeneration of tissues. In the midterm future resorbable stents with incorporated bioactive growth factors have the potential of inducing normal anterior cruciate ligament anatomy without the need for detrimental harvesting of the patient's tissues, or risk of microbial transmission with the use of an allograft. In the near future, the development of more benign autografts and allografts is possible along with methods of resorbable fixation of the graft to bone. Future development of 3-dimensional arthroscopic visualisation and robotic surgical techniques have the potential for improvement in graft placement. Advancements in treatment of anterior cruciate ligament deficient knees also can be expected from nonsurgical areas, such as control of mucscle atrophy, enhancing cerebellar-proprioceptive rehablitation, and better bracing techniques. The basic principle of therapy should be to maximize the functional load acceptance and transference capacity of the knee with the least degree of risk to the patient.
(Back to the list of references)

Ferrari J D, Ferrari D A: The semitendinosus: anatomic considerations in tendon harvesting. In: Orthop Rev (1991 Dec) 20(12):1085-8
The length and course of the semitendinosus tendon was studied in cadaveric specimens. The average length of the tendinous portion was 23 cm. The tendon separates from the other pes anserinus tendons as it passes beneath the semimembranosus muscle, where the deep fascia forms a sling for the tendon; the surgeon should be aware of this anatomy when using tendon strippers.
(Back to the list of references)

Fahey M, Indelicato P A: Bone tunnel enlargement after anterior cruciate ligament replacement. In: Am J Sports Med 22 (3): 410 - 4, 1994.
Radiographic increase in the size of tibial and femoral tunnels have been observed. This retrospective study compared tibial tunnel diameter in 56 autograft and 87 allograft patellar tendon bone-tendon-bone anterior cruciate ligament replacements increase in the size of tibial and femoral tunnels have been observed. This retrospective study compared tibial tunnel diameter in 56 autograft and 87 allograft patellar tendon bone-tendon-bone anterior cruciate ligament replacements whose observed tunnel changes sere correlated with clinical results at 1 year postoperatively. Tibial tunnel sclerotic margins were measured approximately 1 cm below the joint line. Exact tunnel dimensions was calculated by using a magnification factor determined by the interference screw of known diameter within the same tunnel. Average allograft tunnel enlargement was 1.2 mm (-2.5 to 6.0) compared with the autograft tunnel enlargement of 0.26 mm (-2.5 to 2.7); the difference was significant (P > 0.0002).No significant difference was seen in KT-1000 arthrometer measurements between autograft or allograft groups, and no correlation was seen between increased tunnel size and clinical outcome as determined by the modified Hughston knee evaluation system. Tunnel measurement reproducibility was confirmed by independent repeated measurements. The significance of this tunnel enlargement is unknown and does not appear to adversely affect clinical outcome of allograft utilization. Possible explanations include an immune response with resorption, stress shielding proximal to the interference screw resulting in resorption, or an inflammatory response by synovium in the tunnel.
(Back to the list of references)

Grana W A, Egle D M, Mahnken R, Goodhart C W: An analysis of autograft fixation after anterior cruciate ligament reconstruction in a rabbit model. Am. J. Sports Med., 22: 344-351, 1994.
Fixation and incorporation of a tendon implanted within the bone pose theoretical as well as practical concerns for the surgeon who treats instability problems of the knee. Understanding the physiology involved in graft-bone incorporation is necessary for the appropriate rehabilitation of patients who undergo anterior cruciate ligament surgery. The purpose of the study was to examine the histologic and biomechanical changes of a semitendinosus autograft reconstruction of the anterior cruciate ligament in a rabbit model at the graft-bone tunnel interface in the femur. The results indicate that by 3 weeks, failure of the bone-graft-bone or construction is through the intraarticular portion of the graft, not as a result of pullout from the bone tunnel. Graft fixation of the bone tunnel occurs by an intertwining of graft and connective tissue and anchoring of connective tissue to bone by collagenous fibers and bone formation in the tunnels. The collagenous fibers have the appearance of the Sharpey's fibers seen in an indirect tendon insertion.
(Back to the list of references)

Ishibashi Y, Rudy T, Kim H S, Fu F H, Woo S L-Y: The effect of ACL graft fixation level on knee stability. Procs. AANA, San Francisco, 1995.
Recently, endoscopic reconstruction of the anterior cruciate ligament (ACL) using a single incision has gained popularity. Unfortunately, the mismatch in the lengths of the bone-patellar tendon-bone (BPTB) graft and the tibial tunnel sometimes necessitates a change in the length of the tunnel or possibly graft fixation outside the tunnel. With the recently developed customized bone-hamstring-bone autograft, the graft length can be modified to obtain more anatomical fixation. Therefore we evaluated the stability of the knee with different tibial fixation levels.
Methods: New robotics technology was used to reproduce multiple degree-of-freedom (DOF) knee-joint motion in 20 fresh porcine cadaver knees. First, the robot learned the natural 5-DOF) path of the intact knee-joint under anterior loads up to 11o N and also recorded displacement with the knee flexed to 60 and 90. Next, the knee was reconstructed with a patellar tendon in a simulation of the endoscopic technique. The proximal site of the graft was fixed at the femoral insertion of the ACL for all the tests. The distal site of the graft was fixed sequentially at three different levels for each specimen: (1) "0utside," the graft being fixed just outside the tibial tunnel; (2) "central," the graft being fixed at the central pint of the tibial tunnel; and (3) "anatomical," in which the graft was fixed at the ACL insertion site. For each level, the 5-DOF anterior tibial displacement was recorded for loads up to 110 N, and these data were compared with corresponding data for the intact knee.
Results: The anterior displacement of the intact knee was 5.7 +- 2.4 mm (mean +- SD) at 60 of flexion. After reconstruction, displacement increased to 10.5 ++- 2.6 mm (184% of intact), 8.9 +-2.4 mm (156.1 %), and 7.9 +-2.6 mm (138.6 %), respectively, for outside, central and anatomical fixation at 60 of flexion. These differences were statistically significant (p<0.05). The increase in anterior displacement at 90 of flexion were slightly larger: 9.2 mm +-2.1 mm (204%), 8.0 +- 1.9 mm (177.8%), and 6.7 +- 2.1 mm (148.9 %), respectively, for outside, central and anatomical fixation.
Discussion and Conclusion: The level of tibial fixation significantly affected the anterior displacement of the tibia, and the reconstructed knees were most stable (i.e. least displaced) with anatomical fixation. Possible reasons for the differences in results included the different graft lengths and the mismatched diameters of the tibial tunnel and the graft. Results of the present study suggest the best tibial graft fixation level and reconfirm problems of the technique.
(Back to the list of references)

Johnson D L, Either D B, Vanarthos W J: Herniation of the patellar fat pad through the patellar tendon defect after autologous bone patellar tendon-bone anterior cruciate ligament reconstruction. A. case report. Am. J. Sports Med., 24 (2): 201-204, 1996.
The most commonly used autogenous tissue for intraarticular ACL reconstruction is the bone-patellar tendon-bone (BPTB) graft. The use of BPTB autografts has been indirectly associated with or directly implicated in many postoperative complications: patellar fracture, patellar ligament rupture, patellar tendinitis, quadriceps muscle weakness, infrapatellar contracture syndrome, and arthrofibrosis. We report an interesting finding of herniation of the patellar fat pad through the donor site defect in the patellar tendon after autologous ACL reconstruction. To our knowledge, this is a previously unreported occurence.
(Back to the list of references)

Johnson LL: The outcome of a free autogenous semitendinosus tendon graft in human anterior cruciate reconstructive surgery: a histological study. In: Arthroscopy (1993) 9(2):131-42
This report illustrates the outcome of a free human autogenous semitendinosus tendon graft placed in the knee under arthroscopic control for anterior cruciate ligament reconstruction. The tendon graft showed signs of injury by localized loss of normal histochemical staining properties. The cellularity was not diminished in an early (3-week) specimen. The resultant composite anterior cruciate ligament consisted of two distinct areas: tendon graft and surrounding fibrous tissue. The tendon maintained gross and microscopic characteristics of the original tendon. The tissue surrounding the tendon graft had a disorganized cellular pattern and hypervascularity. The tendon graft in this study did not show gross or microscopic evidence of death and reorganization. Previous reports have led to erroneous conclusions concerning the outcome of a free tendon graft due to inaccurate biopsy site of the reorganizing fibrous tissue surrounding the tendon graft.
(Back to the list of references)

Johnson LL: Comparison of bioabsorbable and metal interference screws in anterior cruciate ligament reconstruction: a clinical trial. Procs. AAOSM, San Franzisco, 1995.
The purpose of this study was to determine if a biodegradable interference screw was as safe and effective as a metal screw of the same design used for the same purpose; anterior cruciate ligament reconstruction.
Method: Experienced orthopedic surgeons were recruited to participate in one of two groups for this study. No financial incentive was offered to either the institution, surgeon or the patient for participation. The surgeons and their patients were devided into two groups; Group I (Biodegradable screw), Group II (Metal screw). The qualified patient had to have functional instability due to anterior cruciate ligament instability of the knee, but without severe degenerative arthritis. The success criteria included the restoration of functional stability supported by clinical examination measurement. Failure criteria included continued functional instability , presence of clinical signs of inflammation, x-ray evidence of bone cyst formation, or migration of the tendon graft bone blocks. The surgery was performed using both arthroscopic and open techniques. The substitute donor graft tissue was patellar bone tendon bone in all cases. Group I (Biodegradable screw): There were four centers and four surgeons recruited for this trial. There were 57 patients in this group. There were 43 autogenous and 14 allografts utilized. Group II (Metal screw): There were two centers and two surgeons recruited for this trial. There were 34 patients in this group. All 34 patients had an autogenous graft utilized. Follow-up clinical evaluations were conducted at six months and again at one year.
Results: The results showed restoration of anterior cruciate ligament functional stability in all patients. There were no infections, no neurovascular injury, nor thromboembolic complications. Three patients in the biodegradable group underwent re-operations for reasons unrelated to the device. Two were for ankylosis and one for subsequent injury. There were no re-operations in the metal group. There was no evidence for inflammation to the bioabsorbable material noted by clinical examination or by x-ray review. The lack of inflammation was supported by biopsy of the screw site of the three re-operated patients. Both the bioabsorbable and the metal groups showed same statistical results.
Conclusion: This bioabsorbable screw was both safe and effective for the intended purpose and comparable to the metal screw of the same design.
(Back to the list of references)

Kurosaka M, Yashiysa, S Andrish J T: A biomechanical comparison of different surgical techniques of graft fixation for anterior cruciate ligament reconstruction. Am. J. Sports Med., 15: 225-229, 1987.
Different surgical methods of graft fixation in ACL reconstruction were examined to determine the effects on mechanical properties of the reconstructed ACL. Ten human cadavers were used in this study. Six different types of grafts were studied. The tendon grafts were removed from each cadaver and fixed to femurs and tibias as ACL substitutes with different surgical fixation methods, leaving femur-reconstructed graft-tibia preparations. The surgical techniques used were staple fixation, tying sutures over buttons, and screw fixation. In the latter, the screws were introduced through femoral and tibial drill holes from the outside in order to achieve interference fit as described by Lambert. Tensile testing demonstrated that the original ACL is significantly stronger than the graft used for reconstruction in linear load, stiffness, and maximum tensile strength. All of the failures of the reconstructed ACL grafts occurred at the fixation site, indicating that the mechanically weak link of the reconstructed graft is located at the fixation site. Among the different methods of fixation, one-third of the patellar tendon secured with a cancellous screw, especially with a custom designed large diameter screw, showed significantly higher values. Although many other factors affect the success of ACL reconstruction, our study indicates that the method of surgical fixation is the major factor influencing the graft's mechanical properties in the immediate postoperative period.
(Back to the list of references)

Lipscomb A B, Johnston R K, Snyder R B, Warburton M J, Gilbert P P: Evaluation of hamstring strength following use of semitendinosus and gracilis tendons to reconstruct the anterior cruciate ligament. In: Am J Sports Med (1982 Nov-Dec) 10(6):340-2
Reconstruction of the anterior cruciate ligament using the semitendinosus and gracilis tendons combined with the appropriate extraarticular procedures has been performed by the authors in 482 cases. In 321 cases both the semitendinosus and gracilis tendons were used and in 161 the semitendinosus alone. This retrospective study was done to determine if the use of these two tendons resulted in any significant loss of hamstring strength. Evaluation of quadriceps strength was also done as a measure of postoperative rehabilitation. Fifty-one patients with an average follow-up time of 26.2 months were tested on the Cybex machine (Cybex Co., Ronkonkoma, New York) by two examiners using the same technique. The examiners had not participated in the surgery or rehabilitation of these patients. In the reconstructed knee in which both semitendinosus and gracilis were used, hamstring strength was found to average 99% compared to the normal knee. When the semitendinosus alone was used there was no difference (102%) from the normal knee. Quadriceps strength in both groups averaged 96% in comparison to the normal quadriceps. These results confirm that no significant loss of hamstring strength occurred when the semitendinosus and gracilis tendons were used to construct the anterior cruciate ligament. Further, quadriceps strength of 96% as compared to the normal knee indicated a very acceptable degree of postoperative rehabilitation in this series.
(Back to the list of references)

Liu S H, Kabo J M, Osti L: Biomechanics of two types of bone-tendon-bone graft for ACL reconstruction. J. Bone Joint Surg., 77-B, 232-235, 1995.
We measured the initial fixation strength of a new graft, bone-hamstring-bone (BHB), for reconstruction of the anterior cruciate ligament (ACL) in 79 porcine knees and compared it with that of the normal porcine ACL and of the bone-patellar tendon-bone (BPB) graft. All specimens were subjected to ultimate load to failure and cyclic loading tests to asses the amount of graft slippage-
The ultimate load to failure for the intact ACL was 1266 250 N, for the BPB graft 663 +- 192 N and for the BHB 354 +- 92 n (P<00.1). After cycling to 235 N (the maximum load for all groups without failure) the average residual displacements after removal of the load for the ACL, BPB and BHB grafts were 0.031 0.013 cm, 00.78 +- 0.033 cm, and 0.322Q- 0.222 cm, respectively (p<0.01) For the BHB graft the load to failure was less and the amount of graft slippage was more than for the BPB graft. Neither form of reconstruction was as strong as the intact ACL.
(Back to the list of references)

Marder R A ,Raskind J R, Carroll M: Prospective evaluation of arthroscopically assisted anterior cruciate ligament reconstruction. Patellar tendon versus semitendinosus and gracilis tendons. In: Am J Sports Med (1991 Sep-Oct) 19(5):478-84
Eighty consecutive patients with chronic laxity due to a torn ACL underwent arthroscopically assisted reconstruction with either autogenous patellar tendon or doubled semitendinosus and gracilis tendons. Reconstructions were performed on a one-to-one alternating basis. Preoperatively, no significant differences between the two groups were noted with respect to age, sex, level of activity, and degree of laxity (chi square analysis). A standard rehabilitation regimen was used for all patients after surgery including immediate passive knee extension, early stationary cycling, protected weightbearing for 6 weeks, avoidance of resisted terminal knee extension until 6 months, and return to activity at 10 to 12 months postoperatively. Seventy-two patients were evaluated at a minimum of 24 months postoperatively (range, 24 to 40 months). No significant differences were noted between groups with respect to subjective complaints, functional level, or objective laxity evaluation, including KT-1000 measurements. Seventeen of 72 patients (24%) experienced anterior knee pain after ACL reconstruction. Overall, 46 of 72 patients (64%) returned to their preinjury level of activity. Mean KT-1000 scores were 1.6 +/- 1.4 mm for the patellar tendon group and 1.9 +/- 1.3 mm for the semitendinosus and gracilis tendons group. This study did find a statistically significant weakness in peak hamstrings torque at 60 deg/sec when reconstruction was performed with double-looped semitendinosus and gracilis tendons.
(Back to the list of references)

Morgan C D, Kalman D O, Grawl D M: Isometry testing for Anterior cruciate ligament reconstruction revisited. Arthroscopy, 11, 6: 647-659, 1995.
The purpose of this study was to determine the efffect, if any, that varying the distal testing position (tibial level) has on isometry data produced with a common anatomic proximal tesing position at the nativ anterior cruciate ligament (ACL) origin. During ACL reconstruction in 25 knees, in vivo isometry measurements were recorded using two different isometry testing methods, which differed in the tibial level of the distal fixation testing point. Method 1 tested distally at a point 13 cm peripheral to the native ACL insertion on a vector in line with the tibial tunnel. Method 2 tested distally at a point central in the native ACL at the level of the intercondylar floor. All tibial tunnels were standardized with similar sagital tunnel-plateau angles and similar tunnel lengths. The proximal testing point were standardized at a point that was anatomically located at or near the central ACL origin 7 mm anterior to the "over the top" in all knees. Using this methods, length changes between the proximal and the distal testing points were recorded in each knee with each testing method, with the knee ranged from 70 of flexion to full extension and from 70 to 140 of flexion. From these data, a total excursion from 0 to 140 was calculated. A nonanatomic distal insertion point (method 1) produced a 6 mm +- 1 mm total excursion, whereas anatomic testing points in the same knees produced a 1 mm +- 1 mm total excursion. From these data, the authors conclude that the tibial level of the distal isometry testing point has a significant effect on the resultant isometry measurement such that anatomic testing points are most isometric. Isometers that that produce data between nonanatomic testing points should not be used to position tunnels for ACL redonstruction and should not be used to assume the elongation forces an ACL substitute will see when fixed at different points. Conversely, the clinical relevance of this study is that both anatomic graft position and anatomic graft fixation positions are important and, when achieved, should result in minmal graft elongation with early postooperative range of motion, leading to a more stable long-term result.
(Back to the list of references)

Mott HW: Semitendinosus anatomic reconstruction for cruciate ligament insufficiency. In: Clin Orthop (1983 Jan-Feb)(172):90-2
Semitendinosus anatomic reconstruction (STAR) rebuilds the major anatomic bands of the anterior cruciate ligament (ACL) and provides isometric ligamentous relationships. STAR secures a graft firmly enough to allow intraoperative testing and early motion. It provides a graft comparable in strength with a normal ACL and salvages the insufficient cruciate ligament even after other procedures have failed. Although technically difficult, this procedure can be accomplished in approximately one hour after it has been mastered. During more than four years of experience, STAR has been a predictable and reliable method for anterior cruciate acute augmentation, as well as reconstruction for chronic cruciate ligament insufficiency.
(Back to the list of references)

Otero A L, Hutcheson L: A comparison of the doubled semitendinosus/gracilis and central third of the patellar tendon autografts in arthroscopic anterior cruciate ligament reconstruction. In: Arthroscopy (1993) 9(2):143-8
The purpose of this study was to compare the postoperative success and stability of two different autografts used to reconstruct the anterior cruciate ligament (ACL): doubled semitendinosus/gracilis (DST&G) and bone-patellar tendon-bone (PAT). Ninety-one young (x = 25.4 years), active patients were available for an average follow-up of 36.4 months and included 55 patients in the PAT group and 36 in the DST&G group. No patients had previously undergone ACL reconstruction. Knee stability data were obtained yearly and included scores from the Lysholm questionnaire, Lachman exam, and KT-1000 arthrometer at 30 pounds (KT30) and maximum pull (KTMAX). Both autografts were of comparable size, tension, and isometricity. Two separate factorial multivariate analyses of variance (MANOVA) were used to compare the two series for 3 follow-up years in the categories acute and chronic (A versus C) and meniscectomy and no meniscectomy (M versus NM). Results indicated that in all categories and follow-up years, PAT patients had consistently greater knee stability compared with the DST&G group. Overall MANOVA results showed significantly lower (p 0.01) Lachman scores in PAT versus DST&G in each of the 3 follow-up years. Significantly lower (p 0.05) KT30 and KTMAX values were also observed for PAT compared with DST&G in year 1. MANOVA results also showed lower (p 0.01) Lachman scores in PAT-A versus DST&G-A for 3 follow-up years. Lachman scores in PAT-NM patients were lower (p 0.01) for postop years 1 and 2 compared with DST&G-NM.
(Back to the list of references)

Pagnani M J, Warner J J, O'Brien S J, Warren R F: Anatomic considerations in harvesting the semitendinosus and gracilis tendons and a technique of harvest. In: Am J Sports Med (1993 Jul-Aug) 21(4):565-71
Although the semitendinosus and gracilis tendons have long been used in ligamentous reconstruction procedures of the knee, their anatomic relationships have not been explicitly detailed. Therefore, cadaveric dissections were performed on fresh-frozen adult knees to examine these relationships. Several key anatomic points are useful in the harvest of these tendons. Their conjoined insertion site is medial and distal to the tibial tubercle. They become distinct structures at a point that is farther medial and slightly proximal. Tendon harvest is facilitated by identifying the tendons proximal to this point. The superficial medial collateral ligament lies deep to the tendons in this area and should not be disturbed. The tendons are ensheathed in a dense fascial layer that may impede tendon stripping. The accessory insertion of the semitendinosus tendon (which was present in 77% of the knees dissected) should be identified and transected to avoid tendon damage at harvest. Knee flexion may reduce the risk of injury to the saphenous nerve as it crosses the gracilis tendon. Variation in tendon diameter affects graft strength.
(Back to the list of references)

Pinczewsky L, Roger G: A new technique of hamstring tendon fixation in endoscopic ACL Reconstruction utilizing a soft threaded interference screw (RCI) In: Operative Technique Manual, Smith & Nephew Donjoy Inc. Carlsbad, CA 92008, USA.

(Back to the list of references)

Pierz K, Baltz M, Fulkerson J: The effect of Kurosaka screw divergence on the holding strength of bone-tendon bone grafts. In: Am J Sports Med, 23 (3): 332-335, 1995.
Fresh-frozen porcine knees were used to demonstrate the effects of diverging Kurosaka screws placement on linear load to fair in simulated anterior cruciate ligament reconstructions. Screws, placed anteromedially (rear-entry or tibial type) or intraarticularly (endoscopic femoral type) into each tibia, were directed at 0, 15, or 30 divergence angles relative to a guide wire. Grafts were axially loaded to failure to determine holding strength. Hierarchical analysis of variance was used to analyse differences between tibial side and endoscopic femoral type screw placement and the angles of divergence. Overall, the difference in pullout strength between rear-entry (or tibial side) an endoscopic femoral type fixation was shown to be statistically significant (P<0.001). Anteromedially placed screws showed a statistically significant decreases in holding strength at 15 and 30 compared with 0 of divergence (P <=".05)." Intraarticular screw placement resulted in a statistically significant decrease in holding strength only at 30 of divergence (P < 0.05). This study supports the importance of accurate screw placement within the tibia to ensure optimal interference fixation and suggests that endoscopic screw placement may offer significant added security when there are minor degrees of divergence.
(Back to the list of references)

Rodeo S A, Arnoczky, P Torzilli A A, Hidaka C, Warren R F: Tendon-healing in a bone tunnel. A biomechanical and histological study in the dog. J. Bone Joint Surg., 77-B(6): 901-905, 1995.
Our study evaluated tendon-to-bone healing in a dog model. Twenty adult mongrel dogs had a transplantation of the long digital extensor tendon into a 4.8-millimeter drill-hole in the proximal tibial metaphysis. Four dogs were killed at each of five time-periods (two, four, eight, twelve, and twenty-six weeks after the transplantation), and the histological and biomechanical characteristics of the tendon-bone interface were evaluated. Serial histological analysis revealed progressive reestablishment of collagen-fiber continuity between the bone and the tendon. A layer of cellular, fibrous tissue was noted between the tendon and the bone, along the length of the bone tunnel; this layer progressively matured and reorganized during the healing process. The collagen fibers that attached the tendon to the bone resembled Sharpey fibers. High-resolution radiographs showed remodeling of the trabecular bone that surrounded the tendon. At the two, four, and eight-week time-periods, all specimens had failed by pull-out of the tendon from the bone tunnel. The strength of the interface was noted to have significantly and progressively increased between the second and the twelfth week after the transplantation. At the twelve and twenty-six-week time-periods, all specimens had failed by pull-out of the tendon from the clamp or by mid-substance rupture of the tendon. The progressive increase in strength was correlated with the degree of bone ingrowth, mineralization, and maturation of the healing tissue, noted histologically. Clinical Relevance: Since the site at which a graft is fixed to bone is, mechanically, the weakest area in the early post-transplant period, knowledge of the healing process (for example(of semitedinosus and gracilis tendon grafts in the reconstruction of the anterior cruciate ligament) will lead to a better understanding of haw to improve the initial fixation of graft to bone. It also can aid in the identification of methods to improve the biological healing response of tendon grafts. In addition, the findings of the current study can help clinicians in the planning of the early weight-bearing or range-of-motion rehabilitation modalities for patients who have had a reconstruction of a ligament and aid in the decision when to remove an internal fixation device that has been used for the attachment of a graft. We recommend that a healing ligament be protected for at least eight weeks after reconstruction.
(Back to the list of references)

Ruland C M, Friedman M J, Kollias S L, Foxi J M: Arthroscopic reconstruction of isolated ACL tears: a comparison of the patellar tendon and the double-loop semitendinosus/gracilis autografts. Proc. AANA. Washington, 199677-B(6): 901-905, 1995.
Introduction: Controversy exists regarding the best auto graft for arthroscopically-assisted ACL reconstruction. Published studies comparing the results of patellar tendon autograft vs. hamstring autograft have included patients with significant associated pathology (meniscus tears, chondromalacia or acute chondral injury, patellofemoral symptoms and malalignment, and other ligamentous injuries). The effects of associated pathology on the final results of ACL reconstruction remain undetermined. Purpose: The purpose of this retrospective study was to eliminate the variables of associated pathology and to compare the results, stability, function, and morbidity of arthroscopically-assisted ACL reconstructions using the central third patellar tendon (PT) autograft vs. a double-looped semitendinosus/gracilis (STG) autograft in patients with "isolated" ACL tears.
Methods: A strict criteria to identify isolated ACL tears was used which included: no previous surgery; no other ligamentous injury; no history of patellofemoral symptoms or malalignment; no meniscal pathology; and no chondromalacia or chondral injury. 37 patients (18 PT, 19 STG) with a mean age of 24.5 years were available for a mean follow-up of 58 months (range, 30-89).
Results: The two groups studied were similar except a difference between the two groups was noted regarding gender PT-14M,4F; STG-6M,13F (p<0.008). No significant differences (p> 0.05) were noted between groups with respect to subjective complaints, functional level, return to sports and objective laxity evaluation (Lachman, pivot shift and KT-1000 measurements). Mean KT-1000 scores at 20 pounds and maximum pull were 1.8 mm and 3.5 mm for the PT group and 2.0 mm and 3.6 mm for the STG group. A 0-1+ Lachman was found in 94% and 95%of the PT group and ST groups respectively. A 0-1+ pivot shift was found in 83% and 89% of the patients in the PT and STG groups respectively. Mean HSS scores were: PT, 91.7 (67-100); STG, 90.5 (67-100), with excellent and good results of 89 vs. 84 respectively. 87% of the PT group and 79% of the STG group returned to the same sport or switched to another sport for reasons no due to knee problems. Anterior knee pain (28% vs. 0%, p=0.02) and patellofemoral crepitus (61% vs. 26%, p=0.06) was more common in the PT group. Patellofemoral crepitus involving the nonoperated knee was more common in the PT group (33% vs. 16%). Painful hardware, especially over the tibial fixation (47% vs. 22%, p=0.17) was more common in the STG group.
Discussion and Conclusion: To our knowledge, no prospective or retrospective study comparing different types of autografts for ACL reconstruction has ever attempted to eliminate the variable of associated knee pathology. In this group of patients studied with isolated ACL tears, the overall results, ligamentous stability, function and morbidity for the patellar tendon group and the double loop semitendinosus/gracilis group were comparable. The gender difference between the two groups suggests a surgeon preference for using a PT autograft in males and the double-loop STG autograft in females. Because of this bias, a fully randomized, prospective study needs to be undertaken to solve the existing controversy regarding the best autograft for arthroscopically assisted ACL reconstruction.
(Back to the list of references)

Shelbourne K. D., and Nitz P.: Accelerated rehabilitation after anterior cruciate ligament reconstruction. Am. J. Sports Med., 18: 292-299, 1990.
To overcome many of the complications after ACL reconstruction (prolonged knee stiffness, limitation of complete extension, delay in strength recovery, anterior knee pain), yet still maintain knee stability, we developed a rehabilitation protocol that emphasizes full knee extension on the first postoperative day and immediate weight-bearing according to the patient's tolerance. Of 800 patients who underwent intraarticular ACL patellar tendon-bone graft reconstruction, performed by the same surgeon, the last 450 patients have followed the accelerated rehabilitation schedule as outlined in the protocol. A longer than 2 year follow-up is recorded for 73 of the patients in the accelerated rehabilitation group. On the 1st postoperative day, we encouraged these patients to walk with full weight-bearing and full knee extension. By the 2nd postoperative week, the patients with a 100 degrees range of motion participated in a guided exercise and strengthening program. By the 4th week, patients were permitted unlimited activities of daily living and were allowed to return to light sports activities as early as the 8th week if the Cybex strength scores of the involved extremity exceeded 70% of the scores of the noninvolved extremity and the patient had completed a sport-specific functional/agility program. The patient database was compiled from frequent clinical examinations, periodic knee questionnaires, and objective information, such as range of motion measurements, KT-1000 values, and Cybex strength scores. A series of graft biopsies obtained at various times have revealed no adverse histologic reaction. The evidence indicates that in this population, the accelerated rehabilitation program has been more effective than our initial program in reducing limitations of motion (particularly knee extension) and loss of strength while maintaining stability and preventing anterior knee pain.
(Back to the list of references)

Steiner M E, Hecker A T, Brown C H, Hayes W C: Anterior cruciate ligament graft fixation. Comparison of hamstring and patellar tendon grafts. Am J Sports Med 22:240-6;1994.
This study assessed the tensile properties of hamstring and patellar tendon anterior cruciate ligament reconstructions in older cadaveric knees (age range, 48 to 79 years). Mechanical testing to failure was conducted by translating the tibia anteriorly at 1 mm/sec with the knee in 20 degrees of flexion. The strongest gracilis-semitendinosus graft fixation technique (103% of intact anterior cruciate ligament) had the tendons doubled and secured with soft tissue washers (P < 0.01). However, all reconstructions using gracilis-semitendinosus grafts were significantly less stiff than the intact anterior cruciate ligament specimens regardless of fixation technique (P < 0.01). The highest strength patellar tendon graft fixation technique (84% of intact anterior cruciate ligament) was obtained with a combination interference screw and suture technique. The difference in stiffness between a patellar tendon graft and an intact anterior cruciate ligament was not significant when interference screws were placed at both ends of the graft (P > 0.05). Both types of grafts failed most often on the tibial side. With appropriate fixation, both grafts approximated the intact anterior cruciate ligament in strength, but only patellar tendon grafts secured with interference screws were comparable in stiffness.
(Back to the list of references)

Stahelin A C, Feinstein R, Friederich N: Clinical experience using a bioabsorbable interference screw for ACL reconstruction. Proc. AAOS. Proc. AAOS, Orlando, 1995 and Orthopaedic Transactions, J. Bone Joint Surg 19, 2: 287-288, 1995.
The use of conventional metallic hardware for fixation of the Bone-Patellar tendon-Bone (B-Pt-B) graft in anterior cruciate ligament (ACL) reconstruction carries the risk of immediate or late postoperative complications. In addition, radiological follow-up studies are often distorted. Other non-metallic means of fixation would therefore be preferable. This study evaluated the clinical efficacy of a bioabsorbable interference screw for fixation of the B-PT-B graft in ACL reconstruction. From 1992 to 1993 we inserted 37 lactide-glycolide and 28 polylactide bioabsorbable screws for fixation of B-PT-B grafts in 36 arthroscopically assisted ACL reconstruction procedures. The mean follow-up time was 1 year (range 6-26 months). There were no drop-outs. 10/36 patients have been followed postoperatively for over two years. Clinical examinations (questionnaires, KT-1000), CT scans, MRIs and bone-biopsies were performed 2, 6, 12, 54 and 104 weeks postoperatively. Using the criteria's of the International Knee Documentation Committee the results were normal in 32/36 of the patients and not normal in 4/36 of the patients. Three patients with lactide-glycolide screws developed postoperative sinus tracts at the tibial incision site. They all healed uneventfully. There has been no fixation failure nor have there been signs which might be indicative of an adverse reaction to the lactic-glycolic acid. Sequential MRI studies showed uneventful incorporation of the autograft as well as disappearance of the bioabsorbable screws. There was one common complication: because of the brittleness of lactide-glycolide interference screws the outermost part of the screw broke in two thirds of the cases during insertion of the femoral screw, so that it was as not possible to countersink the screw all the way. This complication did not adversely affect the outcome and no graft fixations had to be revised. Lactide-glycolide and polylactide bioabsorbable interference screws are a promising alternative for B-PT-B graft fixation in ACL reconstruction. Certain drawbacks associated with the use of metallic devices may be avoided with the use of a non-metallic bioabsorbable interference screw. Disadvantages of bioabsorbable versus metallic interference screws are at present their inferior handling characteristics which may often require the use of an additional bone tap. These problems could be solved using a properly designed screw-screwdriver system and a not too quickly degrading noncristalline polymer. A new design of the bioabsorbable screw and its screwdriver mechanism improved the handling characteristics and breakage of the screw does not occur. Our experience has convinced us that the advantages of bioabsorbable screws in ACL-reconstruction are such, that in most cases they will supersede the use of metallic screws.
(Back to the list of references)

Tohyama H, Beynnon B D, Johnson R J, Nichols C E, Renstrom P A: Morphometry of the semitendinosus and gracilis tendons with application to anterior cruciate ligament reconstruction. In: Knee Surg Sports Traumatol Arthrosc (1993) 1(3-4):143-7
The length and cross-sectional area of human semitendinosus and gracilis tendons were measured in both single- and multi-strand configurations for the purpose of anterior cruciate ligament graft preparation. The average lengths of the semitendinosus and the gracilis tendons were 235 +/- 20 mm (mean +/- SD) and 200 +/- 17 mm, respectively. The cross-sectional area of a doubled semitendinosus tendon (two strands) was significantly less than that of a 10-mm-wide patellar tendon graft (P 0.001). The cross-sectional area of the tripled semitendinosus tendon (three strands) and the 10-mm-wide patellar tendon were similar. Doubling of the combined semitendinosus and gracilis tendons (four strands) and tripling of this combination (six strands) resulted in a significantly greater cross-sectional area in comparison to the 10-mm-wide patellar tendon (P 0.05, four strands; P 0.001 six strands). This investigation demonstrates that anterior cruciate ligament grafts fashioned using multiple-strand combinations of the semitendinosus and gracilis tendons result in a cross-sectional area that is comparable to the bone-patellar tendon- bone graft. This is an important finding since cross-sectional area reflects the intra-articular volume of collagenous tissue. This information should be helpful to surgeons considering using the hamstring tendons as an anterior cruciate ligament graft.
(Back to the list of references)

Yasuda K, Tsujino J, Ohkoshi Y, Tanabe Y, Kaneda K: Graft site morbidity with autogenous semitendinosus and gracilis tendons. Am. J. Sports Med., 23: 706-714, 1995.
To distinguish between morbidity caused by harvesting semitendinosus and gracilis tendons and morbidity associated with anterior cruciate ligament reconstruction surgery, we performed a prospective randomized study using 65 patients who underwent anterior cruciate ligament reconstruction using these tendons. The patients underwent either contralateral (N= 34) or ipsilateral (N=31) graft harvest. For the nonoperated knees in the ipsilateral harvest group, isometric and isokinetic strength of the quadriceps and hamstrings muscles increased to approximately 120% of the preoperative value at 12 months after surgery. Compared with these knees, the tendon harvest did not affect quadriceps muscle strength at all. However harvest did decrease hamstring muscle strength for 9 months after surgery. The graft harvest in knees with anterior cruciate ligament reconstruction also did significantly decrease hamstring muscles strength only at 1 month. Activity related soreness at the donor site was rarely restricting and resolved by 3 months. This study demonstrated that the semitendinosus and gracilis tendon graft is a reasonable choice to minimize the donor site morbidity in ligament reconstruction using autografts.
(Back to the list of references)

Back to the list of contents   |  List of references