Level of the semitedinosus and gracilis muscle stumps following tendon harvesting: a cadaveric study

BACKGROUND: To establish the occurrence of regeneration of the semitendinosus and gracilis tendons following their harvesting for anterior cruciate ligament reconstruction, we performed a simulation procedure using 12 lower extremities from six cadavers and studied the length of the muscle stumps that remained distally beyond the knee joint line and recorded their proximity to the popliteal fascia. RESULTS: Six of 12 semitendinosus and gracilis muscles remained beyond the joint line. Nine semitendinosus and eight gracilis muscle stumps were close to the popliteal fascia, while the other stumps were not. The semitendinosus and gracilis muscles that remained beyond the knee joint line and close to the popliteal fascia, even after tendon harvesting, are supposed to increase the likelihood of regeneration of the functional myotendinous junction, compared with muscles not extending to the joint line. CONCLUSIONS: We were convinced by these results of regeneration of the semitendinosus and gracilis tendons following tendon harvesting, which had been reported clinically.     

Semitendinosus muscle in anterior cruciate ligament surgery: Morphology and function

Purpose: To evaluate the fate of the hamstring muscles in general and the semitendinosus muscle in particular, after anterior cruciate ligament (ACL) reconstruction with an autologous semitendinosus tendon graft from the ipsilateral side. Type of Study: Prospective consecutive case series investigation. Methods: Included were 16 consecutive patients, 14 male and 2 female, with a mean age of 26 years. The inclusion criterion was chronic unilateral ACL insufficiency with no concomitant knee ligament injuries. ACL reconstruction was performed with a quadruple semitendinosus tendon graft using the EndoButton technique (Acufex, Mansfield, MA). Intraoperatively, muscle specimens were taken from the semitendinosus muscle on the harvested side. Follow-up at a minimum of 6 months included clinical examination, isokinetic strength performance, magnetic resonance imaging (MRI) of the thigh and knee, and ultrasound-guided muscle biopsy procurement from the semitendinosus muscle for histochemical and enzymatic analyses. Results: Of the patients, 75% showed regeneration of their semitendinosus tendons. The neotendons all inserted below the knee joint where they had fused with the gracilis tendon to a conjoined tendon inserting in the pes anserinus. The semitendinosus muscle had a smaller cross-sectional area on the operated side but none showed total atrophy. Less atrophy was present in the patients with a regenerated semitendinosus neotendon compared with those without regeneration (P =.029). In the latter group the semimembranosus muscle seemed to compensate for this with hypertrophy (P =.019). Cross-sectional muscle fiber areas, the relative number of each fiber type and oxidative potential as estimated by citrate synthase activity, showed no significant differences between the operated and nonoperated legs. The isokinetic strength of the hamstrings and quadriceps was significantly lower in the operated leg than in the nonoperated leg. Conclusions: With this surgical technique, the semitendinosus muscle can recover and the tendon has, according to the MRI images, a great potential to regenerate after its removal.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 8 (October), 2001: pp 808–817     

术前MRI测量腘绳肌腱横截面积与前交叉韧带重建中移植物的相关性研究

目的:探讨测量MRI腘绳肌腱横截面积在行前交叉韧带重建术前与前交叉韧带重建中移植物的相关性。方法:收集2021年11月至2022年3月在骨关节科拟行前交叉韧带重建术的50例患者的MRI资料,男32例,女18例,年龄19～48(31.1±8.7)岁。术前对半腱肌和股薄肌腱进行MRI测量并记录,然后在关节镜下行前交叉韧带重建术,术中取股薄肌腱与半腱肌腱来制备最终所需移植的肌腱,并且在术中测量已制备好的最终移植物的直径。最后使用统计学软件分析得到数据。结果:MRI测量半腱肌肌腱横截面积、股薄肌肌腱横截面积、半腱肌肌腱与股薄肌肌腱横截面积之和与前交叉韧带术中所需移植物的直径大小呈显著正相关,r值分别为0.858、0.728、0.842(P<0.001),半腱肌肌腱与股薄肌肌腱横截面积之和的曲线下面积(area uder curve,AUC)、灵敏度、和特异性分别为0.925、90.48%、85.71%。结论:在进行前交叉韧带重建术的患者中,术前MRI测量与术中腘绳肌移植直径大小有具有较强的统计学相关性,半腱肌肌腱与股薄肌肌腱横截面积之和对于前交叉韧带重建术中移植物的直径大小有较高的预测价...     

Semitendinosus muscle fatty infiltration following tendon harvest in rabbits

The hamstring tendon autograft is one of the most commonly used graft choices in Anterior cruciate ligament (ACL) reconstruction. There are conflicting results regarding postoperative hamstring strength deficits in patients who have had a hamstring graft. The semitendinosus tendon has been shown to regenerate after harvesting for ACL autograft, suggesting that the muscle has the potential to regain normal function. However, no studies have been performed to define the microstructural changes that occur in the semitendinosus muscle after tendon resection. In this study, we hypothesized that fatty infiltration of the semitendinosus muscle after tendon harvest in New Zealand White rabbits increases postoperatively and remains constant or increases during the first year of repair. The semitendinosus tendon was unilaterally detached and harvested from 15 rabbits. Five rabbits were sacrificed at 3‐, 6‐, and 12‐month intervals, and the semitendinosus muscle‐tendon units were analyzed. The contralateral unoperated limb served as the control. The gross tendon and muscle dimensions and histologic percentage of fatty infiltration were measured. We found no significant difference in fatty infiltration at any time point between the control muscle and test specimens and that there was no progression of fatty infiltration over time. If these results hold true in humans, natural repair of the hamstring muscle following tendon harvest during ACL autograft reconstruction is not inhibited by fatty infiltration. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1234–1239, 2013     

Anatomic double-bundle posterior cruciate ligament reconstruction using hamstring tendons

Recent biomechanical studies have shown that an anatomic double-bundle posterior cruciate ligament (PCL) reconstruction is superior in restoring normal knee laxity compared with the conventional single-bundle isometric reconstruction. We describe a modification of an endoscopic PCL reconstruction technique using a double-bundle Y-shaped hamstring tendon graft. A double- or triple-bundle semitendinosus-gracilis tendon graft is used and directly fixed with soft threaded biodegradable interference screws. In the medial femoral condyle, 2 femoral tunnels are created inside-out through a low anterolateral arthroscopic portal. First, in 80° of flexion, the double-stranded gracilis graft is fixed with an interference screw inside the lower femoral socket, representing the insertion site of the posteromedial bundle. In full extension the combined semitendinosus-gracilis graft is pretensioned and fixed inside the posterior aspect of the single tibial tunnel. The double- or triple-stranded semitendinosus tendon is inserted in the higher femoral tunnel, presenting the insertion site of the anterolateral bundle. Finally, pretension is applied to the semitendinosus bundle in 70° of flexion and a third screw is inserted. Using this technique, the stronger semitendinosus part of the double-bundle graft, which mimics the anterolateral bundle of the PCL, is fixed in flexion, whereas the smaller gracilis tendon part (posteromedial bundle) is fixed in full extension. Thus, a fully arthroscopic anatomic PCL reconstruction technique is available that may better restore normal knee kinematics as compared to the single-stranded isometric reconstruction.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 1 (January), 2001: pp 88–97     

Atrophy of semitzendinosus and gracilis and flexor mechanism function after hamstring tendon harvest for anterior cruciate ligament reconstruction

The cross-sectional areas of individual knee flexors and isokinetic flexion measurements were evaluated using computed tomography in 13 patients following semitendinosus and gracilis tendon harvest for anterior cruciate ligament reconstruction. The atrophy of tendon-dissected muscles demonstrated variance with two peaks: >70% and <50%. In three patients whose semitendinosus and gracilis muscles displayed areas <50% of the contralateral area, the cross-sectional area of the entire flexor group and work at >75 degrees of knee flexion was 88.1% and 51.9%, respectively. Therefore, hamstring tendon harvest can induce atrophy of tendon-dissected muscles and decrease flexor function.     

Hamstring autograft utilization in reconstructing anterior cruciate ligament: Review of harvesting techniques,graft preparation,and different fixation methods

Rupture of the anterior cruciate ligament (ACL) is a common orthopedic injury. Various graft options are available for the reconstruction of ruptured ACL. Using the hamstring muscle as an autograft was first described in 1934, and it remains a commonly harvested graft for ACL reconstruction. Hamstring autografts can be harvested using the traditional anteromedial approach or the newer posteromedial technique. An isolated semitendinosus tendon can be used or combined with the gracilis tendon. There are numerous methods for graft fixation, such as intra-tunnel or extra-tunnel fixation. This comprehensive review discusses the different hamstring muscle harvesting techniques and graft preparation options and fixation methods. It provides a comprehensive overview for choosing the optimal surgical technique when treating patients.     

Effects of early progressive eccentric exercise on muscle structure after anterior cruciate ligament reconstruction

BACKGROUND: Thigh muscle atrophy is a major impairment that occurs early after reconstruction of the anterior cruciate ligament and persists for several years. Eccentric resistance training has the potential to induce considerable gains in muscle size and strength that could prove beneficial during postoperative rehabilitation. The purpose of this study was to evaluate the effects of progressive eccentric exercise on thigh muscle structure following reconstruction of the anterior cruciate ligament. METHODS: Beginning three weeks after reconstruction of the anterior cruciate ligament, forty patients were randomly assigned to a program involving either twelve weeks of eccentric exercises or a standard rehabilitation protocol. Patients were matched by surgical procedure, sex, and age. The final series consisted of two cohorts of twenty patients each who had been treated with one of two types of graft (semitendinosus-gracilis or bone-patellar tendon-bone), with ten patients treated with each of the two rehabilitation protocols in each graft cohort. To evaluate changes in muscle structure, magnetic resonance images of the involved and uninvolved thighs were acquired before and after training. The volume and peak cross-sectional area of the quadriceps, hamstrings, and gracilis and the distal portion of the gluteus maximus were calculated from these images. RESULTS: The volume and peak cross-sectional area of the quadriceps and gluteus maximus, in both the involved and the uninvolved thighs and in the patients treated with each type of graft, improved significantly more in the eccentric-exercise group (p < 0.001). The magnitude of the volume change was more than twofold greater in that group. No significant differences in any hamstring or gracilis structural measurements were observed between the rehabilitation groups. However, the volume and peak cross-sectional area of the gracilis were markedly reduced, compared with the pretraining values, in the patients who had undergone reconstruction with the semitendinosus-gracilis graft. CONCLUSIONS: Eccentric resistance training implemented three weeks after reconstruction of the anterior cruciate ligament can induce structural changes in the quadriceps and gluteus maximus that greatly exceed those achieved with a standard rehabilitation protocol. The success of this intervention can be attributed to the gradual and progressive exposure to negative work through eccentric exercise, ultimately leading to production of high muscle force.     

Rehabilitation after hamstring anterior cruciate ligament reconstruction

A prospective comparative study was conducted involving 62 patients to determine the effects and limits of accelerated rehabilitation on clinical outcome. The study focused on whether aggressive rehabilitation after anterior cruciate ligament reconstruction with the doubled semitendinosus and gracilis tendon autograft results in stretching the graft. Thirty patients had postoperative rehabilitation according to the current conservative protocol, and 32 patients had rehabilitation using an accelerated regime. Each patient was evaluated subjectively and objectively 36 months or more after surgery. Concerning the side-to-side difference in the anterior laxity, 87% of the patients in the conservative rehabilitation group had 3 mm or less and 80% of the patients in the accelerated rehabilitation group had the same acceptable laxity. There was no significant difference between the two groups. Muscle torque was restored significantly earlier in the patients in the accelerated rehabilitation group than in the patients in the conservative rehabilitation group. Nine months after surgery, however, there were no significant differences in the torque between the two groups. Accelerated rehabilitation significantly increased the incidence of knee effusion during rehabilitation. This study showed that acceleration of postoperative rehabilitation could rapidly restore muscle strength without significantly compromising graft stability in anterior cruciate ligament reconstruction with the doubled hamstring tendon autograft. However, this study also showed that acceleration significantly increases the incidence of synovitis. Acceleration of postoperative rehabilitation has advantages and disadvantages for clinical outcome after anterior cruciate ligament reconstruction.     

Anterior cruciate ligament replacement: comparison of bone-patellar tendon-bone grafts with two-strand hamstring grafts. A prospective,randomized study

BACKGROUND: The purpose of this investigation was to evaluate replacement of a torn anterior cruciate ligament with either a bone-patellar tendon-bone autograft or a two-strand semitendinosus-gracilis autograft to compare the results of clinical testing, patient satisfaction, activity level, functional status, and muscle strength. METHODS: Fifty-six patients with a torn anterior cruciate ligament were enrolled in a prospective, randomized, controlled study. Twenty-eight underwent reconstruction with a bone-patellar tendon-bone autograft, and twenty-eight were treated with a two-strand semitendinosus-gracilis autograft. Patients were followed for an average of thirty-nine months (range, thirty-six to fifty-seven months). At the time of final follow-up, twenty-two patients in each group were evaluated in terms of clinical test findings, patient satisfaction, activity level, functional status, and isokinetic muscle strength. RESULTS: The objective outcome of replacement of the torn anterior cruciate ligament with a bone-patellar tendon-bone graft was superior to that obtained with a two-strand semitendinosus-gracilis graft. At the three-year follow-up interval, the patients in whom a hamstring graft had been used had an average of 4.4 mm of increased anterior knee laxity compared with the laxity of the contralateral, normal knee, whereas the patients in whom a bone-patellar tendon-bone graft had been used had an average of 1.1 mm of increased knee laxity. Fourteen percent (three) of the twenty-two patients with a hamstring graft had a mild pivot shift, and 27% (six) had a moderate pivot shift. Only 14% (three) of the twenty-two patients with a bone-patellar tendon-bone graft had a mild pivot shift, and none had a moderate pivot shift. At the same follow-up interval, the patients in whom a hamstring graft had been used had significantly lower peak knee-flexion strength than those who had a bone-patellar tendon-bone graft (p = 0.039). In contrast, the two treatments produced similar outcomes in terms of patient satisfaction, activity level, and knee function (ability to perform a one-legged hop, bear weight, squat, climb stairs, run in place, and duckwalk). CONCLUSIONS: After three years of follow-up, the objective results of anterior cruciate ligament replacement with a bone-patellar tendon-bone autograft were superior to those of replacement with a two-strand semitendinosus-gracilis graft with regard to knee laxity, pivot-shift grade, and strength of the knee flexor muscles. However, the two groups had comparable results in terms of patient satisfaction, activity level, and knee function.     

Anatomical study of the proximal origin of hamstring muscles

Purpose

It is relatively well accepted that the long head of the biceps femoris and the semitendinosus both originate from the ischial tuberosity as a common tendon. However, it is also widely known that the biceps femoris is consistently injured more than the semitendinosus. The purpose of this study was to examine the origins of the hamstring muscles, to find an anatomic basis for diagnosis and treatment of injuries of the posterior thigh regions.

Materials and methods

Twenty-eight hips of fourteen adult Japanese cadavers were used in this study. In twenty hips of ten cadavers, the positional relationships among the origins on the ischial tuberosity were examined. In eight hips of four cadavers, histological examination of the origins of the hamstrings was also performed.

Results

The origin of the long head of the biceps femoris adjoined that of the semitendinosus. In the proximal regions of these muscles, the long head consisted of the tendinous part; however, the semitendinosus mainly consisted of the muscular part. Some of the fibers of the biceps tendon extended to fuse with the sacrotuberous ligament. The semimembranosus muscle broadly originated from the lateral surface of the ischial tuberosity.

Conclusion

The origins of the long head of the biceps femoris and the semitendinosus are found to be almost independent, and the tendon of the long head is partly fused with the sacrotuberous ligament. The high incidence of injuries to the long head of the biceps femoris could be explained by these anatomical configurations.     

"Cigar Wrap" technique for gracilis augmentation in hamstring anterior cruciate ligament reconstruction.

The use of Hamstring grafts for anterior cruciate ligament reconstruction is becoming increasingly popular. Most surgeons use a four-stranded graft consisting of double-stranded semitendinosus and gracilis tendons. The gracilis tendon, in addition to being smaller in diameter, is often shorter and more diminutive at its muscular end. We developed a technique for supplementing this tendon using excess semitendinosus tendon. This allows enhanced tibial tunnel fit and improved graft fixation.     

Arthroscopic reconstruction of the posterior cruciate ligament with quadruple hamstring tendon graft: a double fixation method

BACKGROUND: Surgical reconstruction is indicated for posterior cruciate ligament (PCL) reconstruction for a grade III or IV injury, combined ligament or meniscus injuries, and chronic symptomatic posterior instability. Considerable controversy continues over the choice of graft tissues. Hamstring tendon has been popular in recent years. The purpose of this study is to prospectively assess the outcomes of PCL reconstruction using quadruple hamstring tendon autograft with a double-fixation technique at minimal 2-year follow-up. METHODS: Only patients who received PCL reconstruction without combined associated posterolateral injury reconstruction were included in the series. A hamstring tendon graft is composed of a quadruple-stranded semitendinosus tendon and gracilis tendon 10 cm in length. An arthroscopic technique using a two-incision method and a double-fixation technique were used. Clinical assessments were performed for 30 patients, of which 27 were available for final outcome analysis. Clinical review of patients included the Lysholm knee scores, International Knee Documentation Committee (IKDC) scores, thigh muscle assessment, and radiographic evaluation. RESULTS: On the Lysholm knee rating, 89% of the patients demonstrated good or excellent results in the final assessment. In the IKDC rating analyses, 56% of the patients revealed 3- to 5-mm ligament laxity. Four patients (15%) had grade II laxity. For the IKDC final rating, 26% were normal and 55% were nearly normal. Seventy-eight percent of the patients had less than a 10-mm difference in thigh girth between their reconstructed and opposite limbs. CONCLUSION: Arthroscopic PCL reconstruction with quadruple hamstring tendon autograft appears to produce acceptable results at a minimal 2-year follow-up. The four-stranded hamstring tendon graft is adequate in graft size and associated with minimal harvesting morbidity. The double-fixation method for the graft could provide a rigid fixation. We believe that this technique could afford good ligament function after reconstruction and could be a reasonably acceptable choice for PCL injury.     

Selective thigh muscle atrophy in trans-tibial amputees: an ultrasonographic study

In trans-tibial amputees, PTB (patellar tendon bearing) prostheses provide almost physiological mobility of the knee joint in the sagittal plane. Nevertheless, there are characteristic adaptations of the knee joint muscles. Myosonography is a suitable method for depicting muscle atrophy and hypertrophy due to muscle dysfunction. The present study was intended to assess anatomical alterations of thigh muscles in trans-tibial amputees wearing a PTB prothesis. Thicknesses and cross-sectional areas of the quadriceps femoris, sartorius, gracilis, semitendinosus and biceps femoris muscles were determined ultrasonographically on both limbs in 17 amputees with a PTB prothesis. The gait was analysed using an optoelectronical system, force plates and surface electromyography of the vastus lateralis and biceps femoris muscles. Quadriceps femoris and sartorius muscles of the amputated extremity exhibited significant atrophy compared with the contralateral limb (reduction of muscle thickness ranged between 11.7% and 30.4%), whereas the gracilis and hamstring muscles were not significantly affected. Even the quadriceps femoris muscle of the non-amputated limb showed a slight atrophy compared with a reference group. Increased echointensities were found predominantly in the quadriceps muscle on the amputated leg. During gait, electromyographical activity within the amputated limb was reduced in the vastus lateralis and increased in the biceps femoris muscle. Even long-term adaptation to PTB prostheses results in characteristic deviation from normal gait. Atrophy occurs in the ventral thigh muscles, predominantly on the amputated leg, whereas the dorsal thigh muscles are hardly affected, probably due to compensatory hyperactivity. Received: 14 March 2000     

Prediction of hamstring tendon autograft diameter and length for anterior cruciate ligament reconstruction

The purpose of this study was to determine whether common physical measurements in patients undergoing anterior cruciate ligament (ACL) reconstruction with autologous hamstring tendon could be used to predict autograft length and diameter. One hundred nineteen consecutive patients undergoing hamstring autograft ACL reconstruction had these preoperative measurements taken: age, height, weight, bilateral leg length, and bilateral thigh girth 5 and 10 cm proximal to the superior pole of the patella. Correlations between these measurements and graft length and diameter were evaluated. There was a strong correlation between leg length and hamstring autograft length (r = .73, P<.001). Weight (r = .51, P<.001) and leg length (r = .42, P<.001) had only moderate correlations with graft diameter. All other correlations were weak. Regression analysis demonstrated that leg length can be used to predict hamstring autograft tendon length to within 20 mm and that weight can be used to predict graft diameter to within 1.2 mm using regression equations. In conclusion, several simple measurements correlate with doubled semitendinosus and gracilis tendon autograft length and diameter. This new information may prove useful to surgeons who want hamstring autografts of a certain diameter or of a long length.     

前交叉韧带重建术后关节镜下股部肌力测量

目的　观察自体中1/3 骨-髌韧带-骨为供区,重建前交叉韧带后对股部肌力的影响。方法　自体中1/3 骨-髌韧带-骨移植重建前交叉韧带术后1年,关节镜下再视观察到无膝内紊乱的患者23 例;男9 例,女14 例。平均年龄为20.8岁。所有患者在关节镜再视术前使用MyretRZ-450型CybexⅡ等速肌肉功能测试器,对患侧和健侧进行股四头肌和腘绳肌的等长(60°和90°)和等速(60°/s和180°/s)肌力测定。结果　自体中1/3骨-髌韧带-骨做为供区,重建前交叉韧带之侧别的股四头肌肌力比健侧的股四头肌肌力明显降低(P< 0.01)。而获取自体中1/3 骨-髌韧带-骨移植后,对腘绳肌肌力则无影响(P> 0.05)。结论　获取自体中1/3 骨-髌韧带-骨移植重建前交叉韧带后,可严重降低股四头肌肌力     

EndoButton drill bit failure

A case of an EndoButton drill bit failure associated with anterior cruciate ligament reconstruction using semitendinosus gracilis autograft is reported. The distal 10 mm flutes of the drill bit sheared off prior to graft passage. This event was likely related to repeated use of this bit, which is intended for single use only. This case highlights another potential pitfall associated with anterior cruciate ligament reconstruction.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 3 (March), 2002: pp 322–324     

The semitendinosus tendon regenerates after resection: a morphologic and MRI analysis in 6 patients after resection for anterior cruciate ligament reconstruction

Recently, the surprising observation has been made, supported by clinical and MRI findings, that the semitendinosus tendon can regenerate after being harvested in its whole length and thickness for anterior cruciate ligament reconstruction. We studied 6 patients with previous anterior cruciate ligament reconstruction, using a quadruple semitendinosus tendon autograft. In 5 of these, physical examination and MRI showed that the tendond had regenerated. In all 6 patients, the findings were documented macroscopically by open surgical exploration and in the 5 regenerated tendons, also morphologically by biopsies. Macroscopically, histologically and immunohistochemically the regenerated tendons closely resembled normal ones with focal scar-like areas. Our present findings and earlier studies show that full length and thickness harvesting of the semitendinosus tendon in most cases result in full-length tendon regeneration with tissue closely resembling the normal tendon.     

The semitendinosus tendon regenerates after resection: A morphologic and MRI analysis in 6 patients after resection for anterior cruciate ligament reconstruction

Recently, the surprising observation has been made, supported by clinical and MRI findings, that the semitendinosus tendon can regenerate after being harvested in its whole length and thickness for anterior cruciate ligament reconstruction. We studied 6 patients with previous anterior cruciate ligament reconstruction, using a quadruple semitendinosus tendon autograft. In 5 of these, physical examination and MRI showed that the tendond had regenerated. In all 6 patients, the findings were documented macroscopically by open surgical exploration and in the 5 regenerated tendons, also morphologically by biopsies. Macroscopically, histologically and immunohistochemically the regenerated tendons closely resembled normal ones with focal scar-like areas. Our present findings and earlier studies show that full length and thickness harvesting of the semitendinosus tendon in most cases result in full-length tendon regeneration with tissue closely resembling the normal tendon.     

The semitendinosus tendon regenerates after resection: A morphologic and MRI analysis in 6 patients after resection for anterior cruciate ligament reconstruction

Recently, the surprising observation has been made, supported by clinical and MRI findings, that the semitendinosus tendon can regenerate after being harvested in its whole length and thickness for anterior cruciate ligament reconstruction. We studied 6 patients with previous anterior cruciate ligament reconstruction, using a quadruple semitendinosus tendon autograft. In 5 of these, physical examination and MRI showed that the tendond had regenerated. In all 6 patients, the findings were documented macroscopically by open surgical exploration and in the 5 regenerated tendons, also morphologically by biopsies. Macroscopically, histologically and immunohistochemically the regenerated tendons closely resembled normal ones with focal scar-like areas. Our present findings and earlier studies show that full length and thickness harvesting of the semitendinosus tendon in most cases result in full-length tendon regeneration with tissue closely resembling the normal tendon.