Reconstruction of the medial patellofemoral ligament for the treatment of habitual or recurrent dislocation of the patella in children.

We investigated the clinical outcome of a reconstructive procedure of the medial patellofemoral ligament for the treatment of habitual or recurrent dislocation of the patella in four children (6 knees), with a minimum follow-up of four years. The technique involves transfer of the tendon of semitendinosus to the patella using the posterior one-third of the femoral insertion of the medial collateral ligament as a pulley. There was no recurrence of dislocation after surgery. The mean Kujala score at follow-up was 96.3 points. Radiological assessment showed that the congruence angle, the tilt angle and the lateral shift radio were restored to normal. The lateral and medial stress shift ratios and the Insall-Salvati ratio remained abnormal. We conclude that this technique can be recommended for the treatment of habitual or recurrent patellar dislocation in children, although hypermobility and patella alta are not fully corrected.

Pretibial cyst formation after anterior cruciate ligament reconstruction using auto hamstring grafts: two case reports in a prospective study of 89 cases.

Eighty-nine cases after anterior cruciate ligaments (ACL) reconstruction were followed prospectively with magnetic resonance imaging (MRI). The patients were examined using axial and sagittal MRI at least twice during the postoperative evaluation of reconstructed ACL. Two cases of pretibial cyst formation were observed. At the time of cyst formation, neither patient had any subjective or objective evidence of knee instability. The cyst of one case communicated with the intra-articular. The minimum follow-up period after the surgical excision was 9 months, with no evidence of recurrence. We might speculate that the critical period for cyst formation in both patients occurred at less than 12 months after their ACL reconstruction. We concluded that the cyst formation was most likely due to incomplete graft tendon incorporation within the osseous tunnel.

Anterior cruciate ligament augmentation under arthroscopy. A minimum 2-year follow-up in 40 patients.

We present a new surgical technique of anterior cruciate ligament (ACL) augmentation using autogenous hamstring tendons or allogenic fascia lata under arthroscopy for patients in whom considerable ACL remnants with mechanoreceptors are preserved. We review the clinical results of 40 patients who underwent this ACL augmentation, as assessed by manual instability tests, KT-2000 knee arthrometer, Lysholm and Gillquist score, joint position sense and magnetic resonance imaging (MRI), and compare them with those of ACL reconstruction. The side-to-side differences of anterior displacement measured by the KT-2000 knee arthrometer at 30 lbs, an average of 5.3 +/- 2.6 mm preoperatively, was significantly improved to an average of 0.7 +/- 1.8 mm in the augmentation group, while an average of 6.0 +/- 2.4 mm was improved to 1.8 +/- 2.1 mm in the reconstruction group. There was no statistically significant difference between the preoperative values in the two groups, but the postoperative values of the augmentation group were significantly less than those of the reconstruction group. The ratio of anterior terminal stiffness of the augmentation group was 1.2 +/- 1.8, and that of the ACL reconstruction group was 0.7 +/- 0.4. This was a statistically significant difference (P < 0.05). Thus, as for the KT-2000 knee arthrometer, the ACL augmentation group showed significantly better anteroposterior stability and terminal stiffness than the ACL reconstruction group. The final inaccuracy of joint position sense of the augmentation group was 0.7 degrees +/- 0.7 degrees, while that of the reconstruction group was 1.7 degrees +/- 1.2 degrees indicating a significant difference (P < 0.05). This study demonstrates that ACL augmentation, which can preserve ACL remnants with mechanoreceptors, is superior to ACL reconstruction from the viewpoint of position sense and joint stability.

The regeneration of sensory neurones in the reconstruction of the anterior cruciate ligament.

We examined whether somatosensory evoked potentials (SEPs) were detectable after direct electrical stimulation of injured, reconstructed and normal anterior cruciate ligaments (ACL) during arthroscopy under general anaesthesia. We investigated the position sense of the knee before and after reconstruction and the correlation between the SEP and instability. We found detectable SEPs in all ligaments which had been reconstructed with autogenous semitendinosus and gracilis tendons over the past 18 months as well as in all cases of the normal group. The SEP was detectable in only 15 out of 32 cases in the injured group, although the voltages in the injured group were significantly lower than those of the controls. This was not the case in the reconstructed group. The postoperative position sense in 17 knees improved significantly, but there was no correlation between it and the voltage. The voltage of stable knees was significantly higher than that of the unstable joints. Our findings showed that sensory reinnervation occurred in the reconstructed human ACL and was closely related to the function of the knee.

Anterior laxity and MR signals of the knee after exercise. A comparison of 9 normal knees and 6 anterior cruciate ligament reconstructed knees.

9 healthy volunteers and 6 patients with anterior cruciate ligament (ACL) grafts underwent anterior knee laxity measurements and MRI examinations of their knees before and after intensive physical exercise. In the volunteer group, anterior displacement of the knee at 89 and 133 newtons of loading, measured with a KT-2000 knee arthrometer, increased after exercise, compared to before it. In addition, anterior terminal stiffness decreased at 133 newtons of anterior loading. In the ACL group, anterior displacement at 89 and 133 newtons of loading also increased, while no difference was found in anterior terminal stiffness before versus after exercise. On MRI, the signal intensity of normal ACLs after exercise was higher than before it. In contrast, the signals from the grafts showed no differences before versus after exercise. Our findings suggest that the ACL grafts are biomechanically and biochemically different from normal ACLs, even 15 months after ACL reconstruction.

Beneficial effect of basic fibroblast growth factor on the repair of full-thickness defects in rabbit articular cartilage.

The effects of exogenous basic fibroblast growth factor (bFGF) on the repair of full-thickness cartilage defects were examined. Four-millimeter diameter, cylindrical defects were made in rabbit articular cartilage and were filled with human recombinant bFGF. The addition of bFGF to the defect induced the formation of a thick cartilage layer composed of chondrocytes and a metachromatic-stained matrix after 6 weeks. The score of the bFGF-treated tissue, as evaluated by a semiquantitative histological scale, was significantly higher than that of the untreated tissue. At 24 weeks, the cartilage-like matrix that contained the proteoglycans and type II collagen was thicker in the bFGF-treated tissue than in the untreated tissue. Immunohistochemical analysis of the tissues at 6-12 weeks with an anti-bFGF monoclonal antibody suggested that a single application of bFGF increased the number of differentiating chondrocytes that synthesized bFGF at a high level. In contrast, immunostaining of the tissues at 6-12 weeks with a monoclonal antibody against proliferating cell nuclear antigen showed that the number of proliferating cells in the bFGF-treated tissue was fewer than in the untreated tissue. These findings suggest that administration of bFGF into cartilagenous defects promotes the differentiation of chondrocytes and their matrix synthesis, and that this growth factor is useful for improving cartilage repair.

Appearance of anterior cruciate ligament autografts in their tibial bone tunnels on oblique axial MRI.

The objective of this study was to observe the changing appearance of human anterior cruciate ligament (ACL) grafts in their tibial bone tunnels by MRI using oblique axial images. One-hundred and eight knees in 75 patients were studied by MRI at 1-33 months after arthroscopic ACL reconstructions using double-looped, autogenous semitendinosus and/or gracilis tendons. Knees with poor stability were excluded from this study. The examinations were performed at 0.2T with spin echo proton density and T2-weighted oblique axial images. Appearances of grafts were mainly described on spin echo proton density images based upon time after surgery. The grafts appeared as homogeneous, low signal intensity areas in the bone tunnels at 1 month after the surgery. Ring-shaped low signal intensity areas were observed along the wall of the bone tunnels in the 2- to 3-month group. In many grafts from this group, each tendinous bundle appeared as a low signal area separated by a high signal intensity area. In all cases in the 4- to 6-month group, the thickness of the ring-shaped low signal intensity area had increased, whereas the thickness of the high signal intensity area had decreased. In almost all of the cases, the interior of the bone tunnel gradually became a homologous low signal intensity region by 7 to 12 months after the surgery. According to these results, it is suggested that the maturation of the tendon-bone interface was completed from 6 to 12 months after the ACL reconstruction.

Isolated posterior cruciate ligament insufficiency induces morphological changes of anterior cruciate ligament collagen fibrils.

We studied the ultrastructural changes of the human anterior cruciate ligament (ACL) with transmission electron micrograph cross-sections following isolated posterior cruciate ligament (PCL) injury. Biopsy specimens were obtained from the proximal third and anteromedial aspect of the ACL. Fourteen patients with PCL-deficient knees at a mean of 22.1 months from injury to surgery and 5 normal knees amputated secondary to malignant tumors or traumatic injuries were used as controls. A significant difference was found in the number of collagen fibrils per 1 microm2 between the PCL-deficient knee group and the control group. There was a significant difference found in the collagen fibril diameter between the PCL-deficient knee group and the control group. The collagen packing density (the percentage of sampled area occupied by collagen fibrils) was also significantly different between the PCL-deficient knee and the control group. The current study shows that an isolated PCL insufficiency can induce morphological changes in ACL collagen fibrils, suggesting that a PCL insufficiency can have adverse effects on other ligamentous structures in the knee joint.

Ganglion cysts of the cruciate ligaments detected by MRI.

Eight patients with ganglion cysts arising from the cruciate ligaments of the knee joint underwent arthroscopic excision after the MR examination. The MR findings, clinical features and arthroscopic findings were evaluated comparatively.

A new guide system for posteromedial portal in arthroscopic knee surgery.

A view through the posteromedial portal is necessary to observe the posterior portion of the knee joint such as the tibial attachment of the posterior cruciate ligament (PCL) or the posterior horn of the medial meniscus, which is barely, visible through anterior portals. Especially in arthroscopic PCL reconstruction, the arthroscopic view through the posteromedial portal is indispensable for boring a tibial bone tunnel that is correctly sited. However, it is difficult to create this portal safely without cartilaginous or meniscal damage. We have produced new guidelines to facilitate the process of creating the posteromedial portal even by inexperienced hands. With a cannulated K-wire and a cannulated rod with sharp teeth, the joint capsule of the posteromedial corner can be penetrated safely with or without viewing the posteromedial corner through the anterolateral portal. Based on our experience of using this guide system, we believe it will be a great help to many orthopaedic surgeons in performing various types of arthroscopic surgery, not only for PCL reconstruction but also for arthroscopic synovectomy.

MR evaluation of human anterior cruciate ligament autograft on oblique axial imaging.

PURPOSE: The purpose was to observe the changing MR appearance of stable anterior cruciate ligament (ACL) grafts on oblique axial images. METHOD: Fifty-five knees in 44 patients were studied with MRI 1-54 months after arthroscopic ACL reconstruction with double-looped autogenous semitendinosus and gracilis tendons. Knees with poor stability were excluded from this study. Examinations were performed at 0.2 T with SE proton density and T2-weighted sagittal and oblique axial images. RESULTS: High signal intensity areas covered the grafts 1-3 months after surgery. The high signal subsequently extended into the intertendinous bundles. The entire graft gradually became a low signal intensity bundle again after 12 months. Grafts were classified by their appearance on the oblique axial images. CONCLUSION: We conclude that high signal intensity can be seen within stable ACL grafts.

Lipoma arborescens in bilateral knee joints.

We report a case of lipoma arborescens of both knee joints. In the face of chronic joint hydrops, it is important to consider lipoma arborescens in the differential diagnosis and to try to make early diagnosis, using magnetic resonance imaging or another means of examination.

Changes in the permeability and histologic findings of rabbit menisci after immobilization.

The knees of mature rabbits were immobilized for 2 to 8 weeks by a long leg cast to examine adverse effects on the meniscus. Some joints were remobilized for 1 to 4 weeks after an immobilization period of either 6 or 8 weeks. Horseradish peroxidase was injected into knee joints, and the degree of permeation into the meniscus was visualized with diaminobenzidine tetrahydrochloride. Menisci were examined histologically by light and transmission electron microscopic study. Injected horseradish peroxidase permeated all areas of the meniscus in nonimmobilized joints. However, permeability of horseradish peroxidase gradually decreased with increasing time of immobilization and was restricted to the superficial layer of the meniscus in the 8-week immobilization group. Degenerative changes in the deep layers of the meniscus were noted in the 6-week immobilization group: 8 weeks of immobilization induced additional degenerative changes. Although permeability of horseradish peroxidase gradually recovered with remobilization, the degenerative changes remained in the deep meniscal layer in the 8-week immobilization group, even after 4 weeks of remobilization. These results clearly show that long-term immobilization of the knee joint causes adverse changes in the meniscus.

Treatment of articular defects with meniscal allografts in a rabbit knee model.

Deep-frozen allogeneic meniscal grafts for the treatment of articular cartilage defects were performed experimentally. Osteochondral defects 3 mm in diameter were created bilaterally on the medial femoral condyles of 50 Japanese white rabbits. A meniscus was then grafted into the defect in the left knee, and the right knee was left untreated. At various periods from 2 to 24 weeks postoperatively, the rabbits were killed and macroscopic and histologic examinations were performed. Two weeks after operation, the grafted meniscus was bonded to the floor of the defect. After 12 weeks, chondrocytes producing matrix granules was shown by electron microscopy. After 24 weeks, a congruous articular surface was formed. With time, cellular elements infiltrated into the graft from the surrounding tissues, and gradually increased in penetration. Weight bearing in the early stage after operation did not degrade the grafted menisci, and no changes were shown in the opposing cartilage of the tibia. Deep-frozen allogeneic menisci may be useful as a biological implant to repair articular cartilage defects in this model.

A case of steroid-induced osteonecrosis of femoral condyle treated surgically.

The clinical course and the established treatment for steroid-induced osteonecrosis of the femoral condyle have not been clarified yet, mainly because of the limited number of reports. Conservative treatment for steroid-induced osteonecrosis of the femoral condyle has been advocated, because the underlying disease tends to be serious and multiple joints are usually involved. Conservative treatment usually is continued until osteonecrosis becomes extensive and osteoarthritis has progressed enough to justify total knee arthroplasty. Reported here is a case of steroid-induced osteonecrosis of the lateral femoral condyle that, according to preliminary results, was treated successfully with a vascularized bone and periosteal graft.

Allogeneic deep frozen meniscal graft for repair of osteochondral defects in the knee joint.

Osteochondral defects in the knee joints of five patients caused by trauma or osteochondritis dissecans were repaired using deep-frozen allogeneic meniscal grafts. Three patients were male and two were female, with a mean age of 26.4 years. The mean follow-up period was 31 months. Postoperative magnetic resonance imaging (MRI) at all periods clearly showed a smooth and congruous articular surface, although the signal intensity of the grafted meniscus was not the same as that of the articular cartilage. Second-look arthroscopy performed approximately 1 year after surgery demonstrated that the grafted meniscus was well bonded to the grafted site, not sunken; there was no gap between the grafted meniscus and the surrounding articular cartilage, indicating that the grafted meniscus functions as a part of the articular surface. Histologic examination revealed that host cells had infiltrated into the meniscus and that cells surrounded by thin collagen fibrils were morphologically similar to fibrochondrocytes. Thus, the acellular grafted meniscus regenerated as meniscal tissue and formed an articular surface, although hyalinization did not occur. Our results suggest that deep-frozen allogeneic meniscal grafting is a useful method to repair osteochondral defects in the knee joint.

The diagnostic value and limitation of magnetic resonance imaging on chondral lesions in the knee joint.

Chondral lesions of the knee joint, which have been detected via arthrotomy or arthroscopy, were examined prospectively and retrospectively through a review of previously obtained magnetic resonance images (MRIs). The study group was composed of 34 men and 29 women whose average age was 24.6 years. Of these 63 patients, there were 72 articular cartilage lesions in 65 knees. On retrospective analysis, the sensitivity of MRI, which was defined as a true positive reading for softening, fragmentation, erosion, and/or a full-thickness loss of cartilage, was 14.3%, 57.3%, 75.0%, and 100%, respectively. Although the sensitivity to early changes of chondral lesions was low, indicating the limitation of MRI at the present stage, it has been demonstrated that MRI can delineate intracartilaginous changes associated with softening and thickening of cartilage that cannot be detected even with arthroscopy. Therefore, it may be worthwhile to perform an MRI as well as arthroscopy to clarify the pathogenesis of internal derangement of the knee.

Arthroscopic and histologic evaluation of anterior cruciate ligaments reconstructed with the Leeds-Keio ligament.

In 62 of the patients who underwent anterior cruciate ligament (ACL) reconstruction with the Leeds-Keio (L-K) artificial ligament, we performed an arthroscopic second look and biopsy of the reconstructed ACL at 8-36 months postoperatively. Arthroscopic findings were classified into two groups according to the tautness of the ligament and the coverage of the implanted L-K ligament with synovial tissue. Histologic results were classified into three groups according to the orientation of the collagen fibers around the L-K ligament, and the arrangement and morphology of the cells. Although our results demonstrated that the implanted L-K ligament had the capacity for tissue induction, no statistically significant correlation was observed between any two results among the arthroscopic, histologic, and clinical data. Therefore, within the time span of our experiment, we could not conclude that the L-K ligament functioned as a scaffold type of artificial ligament. More convincing results must be attained before any firm recommendation can be made for the use of the L-K ligament as a substitute ACL over the autograft or allograft.