M. Monteleone

Anterior cruciate ligament mechanoreceptors. Histologic studies on lesions and reconstruction.

The fate of mechanoreceptors was studied in torn and reconstructed anterior cruciate ligaments in animals and in humans. In untreated anterior cruciate ligament lesions in humans, morphologically normal mechanoreceptors remained in the ligament for 3 months after the injury. After that time, their number gradually decreased. By the 9th postinjury month, only a few free nerve endings were present. Even free nerve endings were totally absent in the biopsy specimens from 1-year-old lesions. In experimental animals, anterior cruciate ligament reconstruction with autologous patellar tendon resulted in the presence of mechanoreceptors in the reconstructed anterior cruciate ligament. When an artificial ligament was used, no mechanoreceptors were found. Morphologically normal mechanoreceptors were present in 2 patients with a lax biologic anterior cruciate ligament reconstruction 9 and 10 years after the operation.

Long-term results of the Leeds-Keio anterior cruciate ligament reconstruction.

This paper discusses the long-term results of the anterior cruciate ligament (ACL) reconstruction with the Leeds-Keio (LK) prosthetic ligament. For this type of reconstruction we used arthrotomy and an arthroscopy-assisted technique. The fixation was obtained with two bone plugs, and the distal portion was also attached with a staple. A postoperative protocol was used with a progressive range of motion and weight bearing after 50 days. We performed 50 LK operations in professional and amateur athletes aged 17–39 years with an isolated anterior instability. We reviewed at follow-up (5–7 years) 37 patients; 8 were lost, and 5 had a subsequent failure. At the Lysholm score the patients were classified: 19 excellent, 13 good, 3 fair, and 2 poor. At the IKDC grading the patients were classified as follows: 2 class A, 22 B, 8 C, and 5 D. The Lachman test was 1+ in 15 patients, 2+ in 7, 3+ in 2, and negative in 13: pivot shift was 1+ in 9, 2+ in 7, 3+ in 2, and negative in 25. Results of the KT 1000 test at 30 Ib side to side was <3 mm in 23 patients, 3–5 mm in 6, 6–10 mm in 6, and >10 mm in 2. In view of the results observed and the progressive deterioration over the years, this procedure should no longer be performed as an ACL substitute.

Graft-tunnel mismatch in endoscopic anterior cruciate ligament reconstruction: Intraoperative and cadaver measurement of the intra-articular graft length and the length of the patellar tendon

Abstract The results of a study conducted on 50 knees endoscopically reconstructed for an anterior cruciate ligament (ACL) lesion with a free bone-patellar tendon-bone graft and 9 cadaver knees are reported. The mean lengths of the patellar tendon (45.48 ± 4.71 mm) and intra-articular ACL graft (20.44 ± 1.98 mm) were measured in the operated knees. The mean length of the tibial bone tunnel (51.62 ± 2.60 mm) was also measured with a tibial guide at 55°. No statistically significant correlation was found between these three measurements. The length of the patellar tendon was weakly correlated with body height. Measurement of the tibial tunnel on the cadaver knees with increasing degrees of inclination revealed a mean length increase of 0.68 mm per degree (confidence limits: 0.49–0.86). Comparison between the tunnel lengths obtained with the guide and those measured with a Kirschner wire showed a mean difference of 2.3 mm. It is thus desirable to make the tunnel about 53 mm long to ensure excellent fixation of a 28 mm bone block with a 25 mm interference screw. Correct measurement of the anatomical structures involved is in any event an essential requirement for proper execution of the surgical technique.

Magnetic resonance imaging versus arthroscopy for the investigation of the osteochondral humeral defect in anterior shoulder instability. A double-blind prospective study.

A double-blind prospective study was done with 15 patients with anterior shoulder instability to determine the diagnostic efficacy of magnetic resonance (MR) imaging versus arthroscopy in the evaluation of chondral or osteochondral lesions of the humeral head. MR produced 6 true positives, 5 true negatives and 4 false negatives, and its accuracy and sensitivity were 60% and 87%, respectively, whereas arthroscopy gave 8 true positives, 5 true negatives and 2 false negatives, with a sensitivity of 80% and an accuracy of 87%. All lesions diagnosed with either method were regarded as positive by definition, with the result that the specificity was always 100%. The differences in diagnosis sprang from the false negatives. The 40% discrepancy between the two methods was probbly due to our distinction in MR between intra- and extraarticular osteochondral lesions. In the first group (the 4 MR false negatives), there were three instances of firstdegree intra-articular lesion and one diagnostic error (third-degree lesion). In the second (the 2 arthroscopy false negatives), the lesions were of the extra-articular type. It is thus advisable to employ both of these methods to ensure the correct diagnosis of a Hill-Sachs lesion, and hence the correct choice of treatment.

The bone-ligament junction: a comparison between biological and artificial ACL reconstruction.

The physiological bone-ligament junction is composed of four zones: ligament, fibrocartilage, calcified fibrocartilage and bone. It plays a very important part in the distribution of mechanical loads applied to ligaments so as to diminish stress concentration or shearing at the interface. This paper examines types of bone and neoligament insertion after anterior cruciate ligament (ACL) reconstruction with a Dacron prothesis, the Leeds-Keio scaffold ligament (LK), patellar tendon with LAD augmentation (PT+LAD) and bone patellar tendon bone alone (PT). The anterior cruciate reconstructions were implanted in 16 sheep via double-isometric bone tunnels without postoperative knee immobilization. Histological examination of the new insertions (using haematoxylin-cosin, Giemsa, Masson, and Mallory stains) was performed following animal sacrifice after 2, 3, 6 and 9 months. A layer of fibrocartilage between the bone and the ligament was observed with PT, followed by a nearly normal insertion after 6 months. With PT, followed by PT+LAD, the augmentation was surrounded by fibrous tissue (also noted inside the LAD). The PT insertion was virtually physiological after 3–6 months. With the LK scaffold, fibrous tissue was noted in and around the scaffold, even after 6 and 9 months. With the Dacron prosthesis, fibrous tissue around the ligament was unaccompanied by ingrowth into the prosthesis. Nerve endings (pacinian corpuscles) were only present in the PT. These findings show that even after 9 months artificial ligaments are separated from bone by fibrous tissue and devoid of the histological and biomechanical features of a physiological junction. PT alone was the only technique that resulted in formation of a structure very similar to the physiological junction, capable of protecting the bone against excessive shearing stress and the tendon against excessive strains.