Is there significant variation in the material properties of four different allografts implanted for ACL reconstruction

The aims of our study were to: (1) determine if there are differences in the material properties of tendon obtained from implanted tibialis anterior, achilles, bone-patella- bone and tibialis posterior allografts; (2) determine the variability in material properties between the implanted specimens. A total of 60 specimens were collected from fresh frozen allografts implanted at ACL reconstruction. Specimens collected included 15 tibialis anterior, 15 tibialis posterior, 15 achilles and 15 bone-patella-bone tendons. Each specimen was mounted in a custom made cryogrip. The mounted specimens were loaded onto a MTS Testline servo-hydraulic testing machine in a uni-axial tensile test configuration. Specimens were subjected to a strain rate of 5% per second until the ultimate tensile stress (UTS), failure strain and high strain modulus was calculated for each specimen after being normalized for specimen dimensions. Individual material properties were tested using one way analysis of variance (ANOVA) and post hoc Tukey’s B test with a P value of <0.05 considered significant. Homogeneity of variance was assessed using the Levene’s test. As a result, no significant difference was found between all four grafts with regards to UTS, failure strain or high strain linear modulus. The UTS was plotted against the modulus demonstrating a linear relationship which is typical of soft tissues. Significant variability in the results were observed. In conclusion, there was no significant statistical difference between the material properties of the four tendon allografts tested. But significant variability in results was observed within groups and between groups, which may provide one explanation for the range of results in allograft ACL reconstruction reported in the literature.     

The role of magnetic resonance imaging (MRI) in assessment of ACL graft failure

Objective

The aim of this work is to assess the role of MRI in the diagnosis of ACL graft failure and detection of complications that may follow ACL reconstruction.

膝关节前交叉韧带损伤及重建后肌肉力量变化的研究

对ACL陈旧性损伤、急性损伤、手术重建以及未损伤对象四个样本组 ,在等长条件下膝关节肌肉屈伸、旋内 ,旋外、内收和外展的力量情况进行了对比测试。共记录了 5 4个研究对象的 80组测试结果。结果表明各样本组肌肉力量比值在不同方向上存在显著性差异。该结果可能有助于解释ACL损伤及重建后神经肌肉系统的补偿机制 ,并提示通过选择性地训练某些肌肉可达到有效的康复效果。     

Anterior cruciate ligament reconstruction with bone-patellar tendon-bone autograft two-incision technique

Anterior cruciate ligament (ACL) reconstruction can be performed with a variety of techniques. Multiple graft sources for reconstruction are also available. The senior author (JRS) has used an arthroscopically assisted technique with 2 incisions that has achieved consistently good results. One incision is made over the patellar tendon, allowing harvest of the bone-patellar tendon-bone graft and tibial tunnel placement and graft fixation. A second lateral incision is used for femoral tunnel placement and fixation. This method has produced predictably good results and avoids some of the potential complications of endoscopic ACL reconstruction.     

MRI of anterior cruciate ligament repair with patellar and hamstring tendon autografts

Objective. Several MRI sequences were used to evaluate the 2-year postoperative appearance of asymptomatic knee with a torn anterior cruciate ligament (ACL) reconstructed with bone–patellar tendon–bone (BTB) and semitendinosus and gracilis (STG) tendon autografts. Design and patients. Two groups with successful repair of ACL tear with BTB (n=10) or STG (n=10) autografts were imaged at 1.5 T with sagittal and oblique coronal proton density-, T2-weighted and sagittal STIR sequences and plain and contrast-enhanced oblique coronal T1-weighted sequences. The appearance of the graft and periligamentous tissues was evaluated. Results. In all 20 cases, the ACL graft showed homogeneous, low signal intensity with periligamentous streaks of intermediate signal intensity on T2-weighted images. In 10 cases, localised areas of intermediate signal intensity were seen in the intra-articular segment of the graft on proton density- and T1-weighted images. The graft itself did not show enhancement in either of the two groups, but mild to moderate periligamentous enhancement was detected in 10 cases. Conclusion. The MRI appearance of ACL autograft is variable on proton density- and T1-weighted images. Periligamentous tissue showing contrast enhancement is a typical MRI finding after clinically successful ACL reconstruction. Received: 22 February 2000 Revision requested: 27 June 2000 Revision received: 21 August 2000 Accepted: 23 August 2000     

Instrumented measurement of in vivo anterior-posterior translation in the canine knee to assess anterior cruciate integrity.

This study was designed to objectively quantify in vivo anterior-posterior canine knee translation relative to anterior cruciate ligament (ACL) integrity. Tibial translation was determined in one knee of 43 crossbreed hounds from radiographs performed while a set anterior and then posterior force was applied to the tibia using a custom designed device. The total (TTT), anterior (ATT), and posterior (PTT) tibial translation were measured (absolute) and normalized to the width of the tibia (normalized). Absolute and normalized TTT was significantly greater in ruptured ACL knees than in partially disrupted (PD) ACL knees, which were significantly greater than in intact ACL knees. ATT and PTT was significantly greater in ruptured ACL knees than in PD or intact ACL knees, which were not significantly different. The sensitivity and specificity of normalized TTT to distinguish knees with intact from PD ACLs were both 100%. Normalized TTT to distinguish knees with PD from ruptured ACLs had a sensitivity and specificity of 100% and 92%, respectively. Intra- and inter-observer intra-class correlation coefficients were 0.84 or higher for all translations. This precise non-invasive technique to assess canine knee translational stability and ACL integrity permits repetitive, objective measurements for diagnostic use and to assess therapeutic intervention efficacy.     

The healed Segond fracture: a characteristic residual bone excrescence

This report describes the natural history of the Segond fracture and documents the radiographic appearance of the healed Segond fracture. The clinical and radiographic records of 129 patients with acute anterior cruciate ligament (ACL) injuries were reviewed. Four (3.1%) of these patients had Segond fractures. On follow-up radiographic examination, seven patients demonstrated a characteristic bone excrescence arising 3–6 mm inferior to the lateral tibial plateau. In four of the five patients for whom acute injury films were available this excrescence arose at the site of the earlier Segond fracture. Healing of such fractures is associated with a characteristic bone excrescence distinct from an osteophyte. This excrescence implies significant internal derangement of the knee.     

Proprioceptive abilities in patients with conservative and surgical treatment of ACL tears

Summary In the present study we evaluated proprioceptive capabilities of the knee joint with a balance test and correlated these findings to parameters which document mechanical stability. We compared 8 conservatively treated and 12 surgically treated patients with ACL-deficient knee joints with a control group of 12 subjects. The balance test was performed with a Kistler force plate. Both the conservatively treated and the surgically treated patients showed significantly higher deviations of their centre of gravity than the control group. This was true not only for the injured leg but also for the noninjured contralateral leg. The differences were most remarkable when comparing the entire distance of centre of gravity deviations during 10 s. Additionally, the conservatively treated patients interrupted the test procedure significantly more frequently than the other two groups. We were not able to document any correlation between proprioceptive function and parameters for joint stability such as anterior drawer, Lachman, pivot shift and KT-1000 measurements. Clinical significance: In patients with conservatively or surgically treated ACL tears the rehabilitation of proprioceptive capabilities is mandatory both for the injured leg and for the noninjured contralateral leg in order to restore the function of the lower extremities. Reconstruction of passive stability alone is not sufficient.      

Diagnosis of an ACL disruption with KT-1000 arthrometer measurements

The KT-1000 was used to measure anterior tibial displacement in three populations: normal subjects (n=120), patients with unilateral acute anterior cruciate ligament (ACL) disruptions (n=105), and patients with chronic unilateral ACL disruptions who were scheduled for ACL reconstructions (n=159). All patients with ACL disruptions were measured with and without anesthesia. Tibial displacement under three loading conditions was measured: 89 N anterior displacement force, manual maximum displacement force, and quadriceps contraction to lift the leg. The measurements of the normal knee in the injured populations were not significantly different from those of the knees in the normal population on any test. The injured knee tested with and without anesthesia was significantly different from the normal knee on all tests. The right-left difference in the normal population as less than 3 mm in 98% of patients in the 89-N test, 97% in the manual maximum test, and 99% in the quadriceps active test. The largest amount of displacement and the greatest difference in displacement between the injured and the normal knee was produced by the manual maximum test. The manual maximum injured-minus-normal knee displacement was 3mm or more in 99% of patients with chronic ACL disruptions and in 95% of patients with acute ACL disruptions.