Biomechanical comparison of hamstring and patellar tendon graft anterior cruciate ligament reconstruction techniques: The impact of fixation level and fixation method under cyclic loading

Purpose: To mechanically test different reconstruction techniques of the anterior cruciate ligament (ACL) under incremental cyclic loading and to evaluate the impact of the level and method of graft fixation on tensile properties of each technique. Type of Study: In vitro biomechanical study. Methods: Four hamstring and 1 patellar tendon reconstruction techniques were performed on 40 young to middle-aged human cadaveric knees (average age, 39 years). An anterior drawer with increasing loads of 20 N increments was applied at 30° of knee flexion. Anatomic, direct interference screw fixation was tested in 2 hamstring and in the patellar tendon groups. Nonanatomic (extracortical) graft anchorage was tested in the remaining 2 hamstring groups with indirect graft fixations on both sides and the combination of indirect tibial and direct femoral fixation. Structural properties were determined throughout the cyclic loading test. Results: The more anatomic reconstruction techniques provided significantly higher structural properties and smaller loss of fixation compared with nonanatomic, extracortical fixation, with indirect repair on both fixation sites resulting in the lowest structural properties. The tibial fixation site was the weakest link in all of the anatomic reconstructions. Patellar tendon fixation with attached bone blocks in both bone tunnels significantly improved construct stiffness and decreased graft slippage. Conclusions: The results of this study suggest that anatomic fixation should be preferred for anchorage of hamstring tendons and linkage materials should be avoided. Direct soft-tissue fixation with interference screws still allows considerable graft slippage, which can be limited by using a bone block or application of a backup or hybrid fixation, especially on the tibial fixation site.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 3 (March), 2002: pp 304–315     

Evaluation of active knee flexion and hamstring strength after anterior cruciate ligament reconstruction using hamstring tendons

Purpose: The purpose of this study was to evaluate active knee flexion range of motion and hamstring strength following hamstring anterior cruciate ligament (ACL) reconstruction. Type of Study: Case control study, consecutive sample. Methods: Seventy-four consecutive patients who had undergone hamstring ACL reconstruction underwent isokinetic muscle strength testing at 2 years post surgery. Measurements of the maximum standing active knee flexion angle with the hip extended were also taken. During isokinetic testing, we evaluated flexion torque at 90° of knee flexion, in addition to the peak flexion torque. We further compared these parameters of muscle strength around the knee for the patients in whom only semitendinosus tendon was harvested as a graft source (ST group), and those from whom the semitendinosus tendon and the gracilis tendon were harvested (ST/G group). Results: Isokinetic testing showed that, in both the ST and ST/G groups, the knee flexor strength of the involved leg was less effectively restored at 90° of knee flexion than at the angle at which the peak torque was generated. Conversely, no significant difference was seen in the side-to-side ratio in either the peak flexion torque or the 90° flexion torque between the groups. The side-to-side ratio in mean maximum standing knee flexion angle was significantly lower in the ST/G group than in the ST group. Conclusions: This study suggests that the loss of knee flexor strength following the harvest of the hamstring tendons may be more significant than has been previously estimated. Furthermore, multiple tendon harvest may affect the range of active knee flexion.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 6 (July-August), 2002: pp 598–602     

Single– versus two–femoral socket anterior cruciate ligament reconstruction technique: Biomechanical analysis using a robotic simulator

Purpose: Although anterior cruciate ligament (ACL) reconstruction with multistrand autogenous hamstring tendons has been widely performed using a single femoral socket (SS), it is currently advocated to individually reconstruct 2 bundles of the ACL using 2 femoral sockets (TS). However, the difference in biomechanical characteristics between them is unknown. The objective of this study was to clarify their biomechanical differences. Type of Study: This is a cross-over trial using cadaveric knees. Methods: Seven intact human cadaveric knees were mounted in a robotic simulator developed in our laboratory. By applying anterior and posterior tibial load up to ± 100 N at 0°, 15°, 30°, 60°, and 90° of flexion, tibial displacement and load were recorded. After cutting the ACL, the knees underwent ACL reconstruction using TS, followed by that using SS, with 44 or 88 N of initial grafts tension at 20° of flexion. The above-mentioned tests were performed on each reconstructed knee. Results: The tibial displacement in the TS technique was significantly smaller than that in the SS at smaller flexion angles in response to anterior and posterior tibial load of ± 100 N, and the in situ force in the former was significantly greater than that in the latter at smaller flexion angles. Furthermore, in the TS technique, the posterolateral graft acted dominantly in extension, while the anteromedial graft mainly resisted against anterior tibial load in flexion. However, in the SS technique, the anteriorly located graft functioned more predominantly than the posteriorly located graft at all flexion angles. Conclusions: The ACL reconstruction via TS using quadrupled hamstring tendons provides better anterior-posterior stability compared with the conventional reconstruction using a single socket.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 7 (September), 2001: pp 708–716     

A survey of the tension applied to a doubled hamstring tendon graft for reconstruction of the anterior cruciate ligament

Purpose: Currently there is no consensus regarding the amount of tension to apply to a graft when reconstructing the anterior cruciate ligament (ACL). We undertook a study to determine whether sports trained orthopedic surgeons tension hamstring tendon grafts maximally during ACL reconstruction, and also whether surgeons tend to load their grafts within a narrow range of tensions. Type of Study: Cross-sectional study. Methods: One fresh-frozen cadaveric knee with appropriately placed femoral and tibial tunnels and five pairs of preconditioned semitendinosus and gracilis tendons were used. Custom-made computer software and a custom-made, load measurement device was employed. Thirteen orthopedic sports medicine physicians from our community took part in the study. Surgeons were asked to tension the graft as they would in surgery and were then asked to tension the graft maximally. Results: The mean and standard deviation of the normal tension (14.8 ± 7.2 lb) was significantly less (P = .005) than the mean maximal tension (22.3 ± 6.9 lb). Conclusions: This study shows that most ACL surgeons do not tension their graft maximally. Moreover, graft tensioning is highly variable among sports medicine orthopedists. These findings revisit the question as to whether tension should be more accurately measured and controlled for intraoperatively.     

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     

Magnetic resonance imaging of bioabsorbale polylactic acid interference screws during the first 2 years after anterior cruciate ligament reconstruction.

Bioabsorbable screws composed of poly(L-lactic acid) (PLA) were used for graft fixation and studied prospectively with serial magnetic resonance imaging (MRI) scans at 8, 16, and 24 months after autogenous patellar tendon anterior cruciate ligament (ACL) reconstruction in 10 patients. Conventional spin echo, proton density, and T2-weighted double echo sequences were obtained, as well as T2-weighted fat-saturated fast spin echo sequences. All but one of the screws (19 of 20) were evident in all serial scans. These showed minimal decrease in size over time. The one screw that had completely disappeared 8 months after reconstruction had cracked during insertion. None of the reconstructed ACL grafts showed clinical instability, persistent effusions, or detectable adverse reactions to the screws. Two patients developed abnormal signal in the tibial tunnel: one developed fluid anterior to the graft, and the other developed increased signal within the graft. The abnormal signal resolved with time in both patients. Other than the preceding changes, no abnormalities were detected on conventional sequences. Fat-saturated fast spin echo sequences showed a variable amount of increased signal around the tunnels, suggesting edema or fibrovascular marrow changes. The changes noted near the tunnels on the fat-suppressed scans most probably represent a general reaction to surgical insult rather than a reaction to the bioabsorbable screws, as similar changes were noted at the patellar harvest site.     

Joint Infection Unique to Hamstring Tendon Harvester Used During Anterior Cruciate Ligament Reconstruction Surgery

Joint infection after anterior cruciate ligament (ACL) reconstruction is a rare but important clinical issue that must be resolved quickly to prevent secondary joint damage and preserve the graft. After careful analysis, we observed 3 infection cases within a 12-month period after ACL reconstruction, which represented an abnormally elevated risk. All reconstructions were performed by the same surgeon and used hamstring tendon allograft. For each surgery, the Target Tendon Harvester (DePuy Mitek, Raynham, MA) was used to harvest hamstring tendons. Through our review, we learned that this instrument was sterilized while assembled. It is our belief that ineffective sterilization of this hamstring graft harvester served as the origin for these infections. We have determined that appropriate sterilization technique involves disassembly of this particular hamstring tendon harvester before sterilization because of the tube-within-a-tube configuration. We have since continued to use the Target Tendon Harvester, disassembling it before sterilization. There have been no infections in the ensuing 12 months during which the surgeon performed over 40 primary ACL reconstructions via hamstring autograft. The information from this report is intended to provide arthroscopists with information about potential sources of infection after ACL reconstruction surgery.     

Comparison of sagittal obliquity of the reconstructed anterior cruciate ligament with native anterior cruciate ligament using magnetic resonance imaging

Purpose: This study was conducted to compare the obliquity of asymptomatic anterior cruciate ligament (ACL) grafts with normal controls using sagittal magnetic resonance imaging (MRI). Type of Study: Case control study. Methods: Sagittal MRIs from 30 patients with a reconstructed ACL graft and from 30 individuals with an intact ACL were reviewed. Reconstructed patients were operated on with a 2-incision technique using a patellar tendon autograft. These selected patients had a normal or nearly normal IKDC score with a 3 mm or less anterior posterior translation on KT-1000 arthrometer testing compared with the intact knee. MRI showed a continuous and homogeneous graft without evidence of roof impingement. Obliquity of the grafted ACL was determined on each lateral MRI by measuring the intersection of the graft line with the tibial plateau plane. These figures were compared with data similarly obtained from 30 individuals with a stable knee and an intact ACL determined by history and physical examination. Results: Graft obliquity in reconstructed patients averaged 67° with a range between 55° and 81°. In normal controls, intact ACL obliquity averaged 51° with a range between 45° and 55°. The difference between the two groups was statistically significant (P <.0001). Conclusions: MRIs of patients with an appropriate tibial tunnel placement in order to avoid notch impingement showed a continuous and homogeneous graft similar to the native ACL, but with a more vertical graft that does not recreate the normal sagittal obliquity. However, according to arthrometer testing, these more vertical grafts can control anterior posterior knee displacement.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 3 (March), 2003: pp 257–261     

Hamstring graft tibial insertion preservation versus detachment in anterior cruciate ligament reconstruction: a prospective randomized comparative study

Background

Anterior cruciate ligament (ACL) reconstruction with hamstring graft (HG) is a commonly performed procedure. Despite the type of reconstruction chosen, the detached HG undergoes a remodeling process known as ligamentization. In order to shorten the ligamentization process, the maintenance of HG tibial insertion, aimed to spare the tendons vascular supply, has been postulated. The aim of this paper is to report the results of a prospective randomized study comparing clinical and MRI results between two different ACL reconstructive procedures with and without HG tibial insertion preservation.

Methods

Forty patients (mean age 27.5 ± 9.5 years) were enrolled and randomly divided into two groups. The study group underwent an ACL reconstruction using a distally inserted HG, while the control group underwent a technique encompassing HG tibial detachment. Subjective and objective IKDC score was administered preoperatively and at 3-, 6-, 12- and 24-month follow-up. Graft morphology was assessed through MRI evaluation performed at 6-month follow-up.

Results

Clinical results were excellent in both groups. Regarding MRI results, a better intra-articular graft morphology was observed in the study group (Tau = 0.313, p = 0.024). No differences in graft integration were noticed.

Conclusion

The main finding of this preliminary study is that preservation of the hamstring tibial insertion seems to enhance graft ligamentization with improved morphology of the intra-articular portion of the graft compared to a detachment of the hamstring tendons from the tibial side. Further well-designed studies with higher number of patients as well as more serial MRI evaluations are required to validate these preliminary findings.

     

Biomechanical evaluation of patellar- and hamstring tendon graft fixation for anterior cruciat ligament reconstruction using a poly-(D, L-lactide) interference screw

Anterior cruciate ligament (ACL) reconstruction using autologous hamstring tendons are being performed more frequently and satisfactory results have been reported. Advantages such as low donor site morbidity and ease of harvest as well as disadvantages like low initial construct stiffness have been described. Recently, it has been demonstrated that graft fixation close to the original ACL insertion sites increases anterior knee stability and graft isometry. Hamstring tendon fixation techniques using interference screws offer this possibility. To reduce the risk of graft laceration, a round threaded titanium interference screw (RCI) was developed. To improve initial fixation strength, fixation techniques for hamstring tendons with separate or attached tibial bone plugs were introduced. However, data on fixation strength do not yet exist. With respect to the proposed advantages of biodegradable implants, like undistorted magnetic resonance imaging, uncompromised revision surgery and a decreased potential of graft laceration during screw insertion, we performed pullout tests of round threaded biodegradable and round threaded titanium interference screw fixation of semitendinosus (ST) grafts with and without distally attached tibial bone plugs. Data were compared with bone-tendon-bone (BTB) graft fixation using biodegradable and conventional titanium interference screws. We used 56 proximal calf tibiae to compare maximum pullout force, screw insertion torque, and stiffness of fixation for biodegradable direct ST tendon and bone plug fixation (group I: without bone plug, group II: with bone plug) versus titanium interference screw fixation (group III: without bone plug, group IV: with bone plug). A round threaded biodegradable poly-(D, L-lactide) (Sysorb) and a round threaded titanium interference screw (RCI) were used. As a control calf bone-tendon-bone (BTB) grafts fixed with either poly-(D, L-lactide) (group V) or conventional titanium (group VI) interference screws were used. ST tendons were harvested either with or without their distally attached tibial bone plugs from human cadavers and were folded to a three-stranded graft. Specimen were loaded in a material testing machine with the applied load parallel to the long axis of the bone tunnel. Maximum pullout force of ST bone plug (group III: 717 N +/- 90, group IV: 602 N +/- 117) fixation was significantly higher than that of direct tendon (group I: 507 N +/- 93, group III: 419 N +/- 77) fixation. Maximum pullout force of biodegradable screw ST fixation was higher than that of titanium screw fixation in both settings. There was no significant difference in pullout force between biodegradable (713 N +/- 210) and titanium (822 N +/- 130) BTB graft fixation or between ST fixation with bone plug and biodegradable screw with BTB fixation. Pullout force of hamstring tendon interference screw fixation can be improved by using a biodegradable implant. In addition, initial pullout force can be greatly improved by harvesting the hamstring tendon graft with its distally attached tibial bone plug. This may be important, especially in improving tibial graft fixation. This study encourages further research in tendon-bone healing with direct interference screw fixation to confirm the potential of this advanced method.     

Premature hamstring graft amputation during harvesting in ACL reconstruction

IntroductionThere are some possible complications during or after hamstring graft harvesting such as premature graft amputation, medial collateral ligament injury and infrapatellar branch of the saphenous nerve injury. Premature graft amputation can occur by inadequate removal of the accessory branches of the hamstring tendons, poor surgical technique and/or too sharp tendon stripper. In this study, we report a case of premature hamstring graft amputation due to degeneration caused by osteochondroma at the posteromedial aspect of the proximal tibia.Case presentationWe reported the case of a 28-year-old Thai male who had an ACL injury was scheduled for ACL reconstruction. In this case, we had planned to use a hamstring graft for double-bundle ACL reconstruction. During the gracilis tendon harvesting, the graft was prematurely amputated by a tendon stripper at the level of the osteochondroma. The premature graft amputation was sent for pathology, which showed degenerated tissue.ConclusionIn cases of osteochondroma at the posteromedial aspect of the proximal tibia, it is a chance of premature hamstring graft amputation. We suggest removing the osteochondroma before harvesting the tendon grafts to avoid the risk of premature graft transection.     

Quadrupled bone-semitendinosus ACL reconstruction: a prospective clinical investigation in 100 patients

Abstract The hypothesis of our study was that a quadrupled bonesemitendinosus tendon graft could combine the advantage of bone-tobone healing with the high cross-sectional area of a quadrupled hamstring graft in ACL reconstruction. ACL reconstruction with a semitendinosus tendon graft was performed on 100 patients with isolated ACL injury from January 1996 to December 1999: femoral fixation was obtained with Endobutton and tibial fixation with Fastlok. Patients were evaluated for standard knee scores and functional strength tests, postoperative pain rating, knee radiographs taken after surgery and at final follow-up, magnetic resonance images at 3 and 6 months, isokinetic flexion-extension and internal-external rotation tests at 3, 6, and 12 months. Computerized laxity analysis was performed at final evaluation. Average surgical time was 85 minutes, including 13 minutes for graft preparation; 90% of the patients were discharged within 24 h. Subjective knee rating was 80%; kneeling test was positive in 7% and Werner score was 44 (range, 30–48). Lachman test was negative in 90% at final evaluation (mean follow-up, 38 months). Sensory changes at the anterior part of the proximal tibia were present in 30% at 3 months and 10% had definite hyposthesia. MRI showed graft incorporation at 3 months. Computerized laxity analysis revealed 90% with less than 3-mm side-to-side differences. Isokinetic testing showed normal hamstring and quadriceps peak torques at 12 months. The functional strength tests were normal by 6 months. Average Noyes score was 87.9, Lysholm score 93, and Tegner activity rating 6.0 (pre-injury, 6.1). IKDC score showed 90 normal or nearly normal knees, 9 abnormal, and one severely abnormal knee. Quadrupled bone-semitendinosus is a viable graft for ACL reconstruction and should be considered, especially in patients with pre-existing extensor mechanism problems.     

A comparison of outcomes at 2 to 6 years after acute and chronic anterior cruciate ligament reconstructions using hamstring tendon grafts

Purpose: To compare short- to intermediate-term outcomes of patients in whom an acute or chronic anterior cruciate ligament (ACL) reconstruction was performed with a hamstring tendon graft. Type of Study: A consecutive case series of patients who had 2-incision, arthroscopically assisted ACL reconstructions with a triple-strand hamstring tendon graft was retrospectively evaluated. Methods: A total of 120 patients were evaluated at a mean of 44 months. The Tegner Activity Scale, individual components of the Cincinnati Knee Rating System, and the modified Lysholm Score were administered to all patients. A total of 93 patients (78%) returned for examination, instrumented ligament laxity testing, radiographs, isokinetic strength testing, and completion of the IKDC Standard Knee Ligament Evaluation Form. Data from patients undergoing reconstructions for acute and chronic ACL deficiencies were compared. The acute group was defined as reconstruction within 6 weeks of injury without recurrent episodes of instability. Results: At surgery, significantly more (P <.05) cartilage abnormalities and partial medial menisectomies were found in the chronic group. At final follow-up, no significant differences (P >.05) were found between the acute and chronic groups for instrumented laxity, muscle strength, knee motion, or sports activity level. The acute group scored significantly higher (P <.05) on the Lysholm scale, Cincinnati Function scale, IKDC subjective assessment, and IKDC rating for pain at follow-up. The final IKDC grade resulted in significantly more (P =.039) normal knees for the acute group; however, 94.1% of acute and 92.9% of chronic knees were graded normal or nearly normal. Conclusions: Hamstring tendons are an excellent graft choice for ACL reconstruction in both acute and chronic injuries. According to the strict IKDC rating system, greater than 90% of all patients can be expected to have a normal or nearly normal knee at short- to intermediate-term follow-up; however, the chronic group will have fewer patients with a rating of normal.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 4 (April), 2001: pp 383–392     

Rotational muscle strength of the limb after anterior cruciate ligament reconstruction using semitendinosus and gracilis tendon

Purpose: To investigate the influence of harvesting semitendinosus and gracilis tendons on the rotational muscle strength of the limb after anterior cruciate ligament (ACL) reconstruction. Type of Study: Prospective study. Methods: We performed a prospective study of 62 consecutive (34 male, 28 female) patients with ACL reconstructions using the semitendinosus and gracilis tendons. The mean age at surgery was 20.8 years. The semitendinosus tendon was harvested in 32 patients (ST group), and semitendinosus and gracilis tendons in 30 patients (STG group). The peak isokinetic torques for extension, flexion, internal rotation, and external rotation were measured before and 12 months after ACL reconstruction using the Cybex 6000B system (Cybex Division of Lumex, Ronkonkoma, NY). The rotational torque was measured at 30°/sec and 120°/sec. Results: Before reconstruction, the mean isokinetic peak torque of the involved limb was decreased in extension and internal rotation. The mean isokinetic peak torque of the involved limb in extension recovered 12 months after ACL reconstruction; however, the weakness in internal rotation persisted. The preoperative weakness of the involved limb in extension and internal rotation recovered in the male patients, but not in the female patients after postoperative rehabilitation. The peak torque of the involved limb in internal rotation was decreased in the STG group, but not in the ST group. Conclusions: The internal rotational torque was influenced by harvesting the semitendinosus and gracilis tendons after ACL reconstruction, especially in female patients and patients from whom the gracilis tendon was harvested. Semitendinosus and gracilis tendons are important for the internal rotation of the limb and it was difficult to compensate for this function. Thus, we recommend harvesting the semitendinosus tendon only if tendon quality is sufficient to further minimize harvesting morbidity.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 2 (February), 2002: pp 177–182     

Serial magnetic resonance imaging evaluation of the patellar tendon after posterior cruciate ligament reconstruction

Purpose: Our purpose was to prospectively analyze serial changes in magnetic resonance imaging (MRI) signal of the bone–patellar tendon–bone autograft when used for posterior cruciate ligament (PCL) reconstruction and to retrospectively determine at mid-term follow-up the relationship between MRI graft appearance and clinical stability in patients who have undergone arthroscopic PCL reconstruction with a bone–patellar tendon–bone autograft. Type of Study: One prospective serial blinded study and 1 retrospective blinded study. Methods: The first part of the study focused on MRI scans obtained at 3, 6, 9, and 12 months postoperatively in a case series of 10 consecutive patients who underwent arthroscopically assisted PCL reconstruction (group A), and of 10 patients who underwent combined ACL-PCL arthroscopic reconstruction (group B). For the second part of the study, MRI scans were obtained in a retrospective series of 10 patients at mid-term follow-up after PCL arthroscopic reconstruction (group C). Signal intensity of 3 zones, corresponding to the proximal, middle, and distal intra-articular graft zones, was evaluated according to the Howell et al. classification. Fiber continuity assessment was performed using a modified Kühne et al. score. The signal intensity of the 3 zones was independently scored. Knee stability was clinically and instrumentally graded according to the IKDC evaluation form (group 4). A multivariance analysis and grouped t test were used for statistical evaluation. Results: In group A, the average MRI evaluation score was 7.65 ± 1.6 at 3 months, 3.8 ± 0.6 at 6 months, 4.75 ± 1 at 9 months and 6.25 ± 1.2 at 1 year. The portion of graft exiting the femoral tunnel exhibited increased signal and faster maturation than the tibial tunnel. In group B (combined ACL-PCL reconstruction), the graft showed slower graft healing with an average MRI score of 4.85 ± 0.7 at 3 months, 1.9 ± 0.7 at 6 months, 3.9 ± 0.9 at 9 months, and 5.3 ± 1.1 at 1 year. At 1 year follow-up, there was no correlation between MRI appearance and stability in group A, even with MRI findings of fiber continuity. However, at long-term evaluation (group C), a strict correlation between MRI appearance and achieved stability was found. Conclusions: The patellar tendon when used for PCL reconstruction requires more than 1 year to achieve a low-signal intensity over its entire course, and the distal zone near the tibial tunnel shows a slower healing process. MRI graft assessment is useful only 1 year or more following PCL reconstruction.     

膝关节镜下自体腘绳肌腱和同种异体肌腱移植重建前交叉韧带对比观察

目的：探讨关节镜下同种异体肌腱和自体腘绳肌腱重建前交叉韧带的疗效。方法：收集32例前交叉韧带损伤病例,单纯前交叉韧带（ACL）损伤29例,与后交叉韧带（PCL）同时损伤3例。分为2组,同种异体肌腱重建15例,男12例,女3例,年龄23～61岁;自体腘绳肌腱重建17例,男11例,女6例,年龄17～57岁。用可吸收或钛挤压螺钉固定,观察并记录治疗后的症状、体征变化和Lysholm评分以及术后6个月的功能康复情况。结果：全部病例均获得随访,时间6～8个月,所有病例无膝前区疼痛,临床症状消失,膝关节功能得到改善。同种异体肌腱重建前交叉韧带5例患者仍出现Lachman征阳性体征,其中1例产生严重的排斥反应,关节镜复查韧带完全吸收。2组患者治疗后Lysholm评分分别为平均（88.5±7.2）分和（93.2±8.5）分,差异无统计学意义（P〉0.05）。结论：关节镜下两种方法重建前交叉韧带都有较好的疗效,同种异体肌腱重建交叉韧带早期有更多的症状,有明显的个体差异,重建交叉韧带尽可能选用自体腘绳肌腱。     

Arthroscopic anterior cruciate ligament reconstruction with quadriceps tendon-patellar bone autograft

BACKGROUND: Surgical reconstruction of the anterior cruciate ligament (ACL) is indicated in the ACL-deficient knee with symptomatic instability and multiple ligaments injuries. Bone patellar tendon-bone and the hamstring tendon generally have been used. In the present study, we describe an alternative graft, the quadriceps tendon-patellar bone autograft, by using arthroscopic ACL reconstruction. METHODS: From March of 1996 through March of 1997, a quadriceps tendon-patellar bone autograft was used in 12 patients with ACL injuries. RESULTS: After 15 to 24 months of follow-up, the clinical outcome for those patients with this graft have been encouraging. Ten patients could return to the same or a higher level of preinjury sports activity. According to the International Knee Documentation Committee rating system, 10 of the 12 patients had normal or nearly normal ratings. Recovery of quadriceps muscle strength to 80% of the normal knee was achieved in 11 patients in 1 year. CONCLUSION: The advantages of the quadriceps tendon graft include the following: the graft is larger and stronger than the patellar tendon; morbidity of harvest technique and donor site is less than that of patellar tendon graft; there is little quadriceps inhibition after quadriceps harvest; there is quicker return to sports activities with aggressive rehabilitation. A quadriceps tendon-patellar autograft is a reasonable alternative to ACL reconstruction in patients who are not suitable for either a bone-patellar tendon-bone autograft or a hamstring tendon autograft.     

In vitro comparison of elongation of the anterior cruciate ligament and single- and dual-tunnel anterior cruciate ligament reconstructions.

This study evaluated strain in the normal anterior cruciate ligament (ACL) and compared it to four different double-strand hamstring tendon reconstructive techniques. Seventeen fresh-frozen knees from 11 cadavers were tested. The strain in the anteromedial and posterolateral bands of the native ACL and their equivalents in four autograft techniques were measured using differential variable reluctance transducers. The anteromedial band of the intact ACL shortened from 0 degree -30 degrees of flexion, then lengthened to 120 degrees; the posterolateral band of the intact ACL shortened from 0 degree - 120 degrees of flexion. Following ACL excision, these knees underwent reconstruction with double-strand hamstring tendons with either single tibial and femoral tunnels, single tibial and dual femoral tunnels, dual tibial and single femoral tunnels, or dual tibial and dual femoral tunnels. With the exception of the dual-band, dual-tunnel technique, all of the procedures placed greater strain on the reconstructive tissues than was observed on the native ACL, after approximately 30 degrees of flexion. These results indicate that dual-band hamstring tendon reconstructions placed with single tibial and femoral tunnels do not address the complexity of the entire ACL. Rather, these procedures appear to only duplicate the effect of the anteromedial band, while perhaps overconstraining the joint as a result of its inability to reproduce the function of the posterolateral band. During rehabilitation following ACL reconstruction, therefore, only from 0 degree - 30 degrees of the graft tissues are not significantly strained. Dual tibial and femoral tunnel techniques should be evaluated further to more closely recreate knee kinematics following ACL reconstruction.