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We report one case of mid-substance injury of the posterior cruciate ligament and two cases of mid-substance injuries of the anterior cruciate ligament in children. Surgical repair with augmentation using the iliotibial band was performed on these patients without the use of transphyseal drill holes. A small strip of the iliotibial band was sutured onto the end of the cruciate ligament stump to augment the remnant. At the most recent follow-up examinations, conducted 5-11 years after surgery, no restriction or discomfort in daily and sport activities was reported, and acceptable levels of function in the injured knees were noted in all patients. [ABSTRACT FROM AUTHOR]

We examined the temporal changes in posterior laxity and MRI findings in acute isolated posterior cruciate ligament (PCL)-injured knees. 35 patients with acute isolated PCL injuries who attended our clinic within 10 weeks of an injury underwent nonoperative treatment, and were chronologically evaluated for posterior laxity and MRI. We divided them in 3 groups, as regards the evolution of laxity and MRI findings. In 20 patients, the degree of posterior laxity was slight throughout the observation periods. In 9 patients, who had severe posterior laxity on their initial visit, the laxity had improved markedly 6 months after injury and did not deteriorate. In 6 patients the severe posterior laxity did not improve during the study. 4 patients whose PCL on MRI was seen as a continuous swollen band having high signal intensity and showed consistently good stability or even an improvement. We conclude that acute isolated PCL injuries with a continuous swollen band on MRI should be treated conservatively for at least 6 months after injury, even if the posterior laxity is severe initially. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study was to investigate factors that influence the prevalence of medial and lateral meniscal injuries at the time of anterior cruciate ligament (ACL) reconstruction in patients with ACL injuries., Methods: Patients with ACL injuries at 9 institutions were enrolled in this multicentre study. Age, sex, duration between injury and surgery, pivot shift test grade, anterior knee laxity determined using the Kneelax 3 arthrometer, and other variables were assessed by logistic regression analysis. Meniscal conditions were evaluated via arthroscopy., Results: In all, 830 patients were enrolled. The prevalence of medial and lateral meniscal tears was 32.0% (266 knees) and 26.5% (220 knees), respectively. Significant factors that influenced the prevalence of medial meniscal injuries were age [odds ratio (OR) 1.03; P = 0.000], side-to-side differences in instrumented anterior knee laxity before surgery (OR 1.12; P = 0.002), duration between injury and surgery (≥ 12 months) (OR 1.86; P = 0.023), and pivot shift test grade (OR 1.36; P = 0.014). Significant factors of lateral meniscal injury were side-to-side differences in anterior knee laxity before surgery (OR 1.12; P = 0.003) and the male sex (OR 1.50; P = 0.027)., Conclusion: Greater anterior knee laxity, age, a longer duration between injury and surgery, and a higher pivot shift test grade predicted medial meniscal injury. Greater anterior knee laxity and the male sex predicted lateral meniscal injury. In patients with ACL injuries, the importance of side-to-side differences in anterior knee laxity should be rediscovered from the viewpoint of meniscal conditions., Level of Evidence: Level III., (© 2021. European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

Background: Recently, medial patellofemoral ligament (MPFL) reconstruction has become a common, widely used procedure to treat patellar instability. However, few reports exist on the long-term outcome after MPFL reconstruction. We elucidated the middle- to long-term outcome after MPFL reconstruction with Insall's proximal realignment. Methods: From 1999 to 2012, 42 knees of 32 patients who underwent MPFL reconstruction with Insall's proximal realignment were reviewed with a minimum follow-up of five years. Patients who could visit our office and receive some designated examinations were included in this study. The re-dislocation rate and patellar apprehension sign postoperatively were evaluated. The Kujala score and Knee Injury and Osteoarthritis Outcome Score (KOOS) were calculated. We assessed the images using plane x-ray and magnetic resonance imaging (MRI). The tilting angle (TA), congruence angle (CA), and lateral shift ratio (LSR) on the plane x-ray were measured pre- and postoperatively and at final follow-up. Using MRI, osteochondral lesions at the patellofemoral joint were evaluated., Results: A total of 20 knees of 15 patients (two male, 13 female) who could visit our office were studied. The follow-up rate was 47.6%. The mean age at operation was 19.9 (11-41) years and mean follow-up was 123 (60-215) months. One knee (5.5%) had a history of postoperative subluxation, and five (25%) had a positive apprehension sign. The mean Kujala score significantly improved from 65.5 to 86.1 points (P < 0.05). The mean KOOS (symptom, pain, activities of daily living [ADL], sports, quality of life [QOL]) was 74.4, 92.4, 97.3, 84.1, and 73.2 points, respectively, at final follow-up. On the plane x-ray, patellofemoral alignment was improved postoperatively, and this improvement was maintained at final follow-up. On MRI, in five of 20 cases, the patellofemoral osteoarthritic change was observed at final follow-up. However, in four of these five knees with severe osteochondral lesions, osteochondral fixation or transplantation surgery had been performed. Only one of the remaining 15 knees had a patellofemoral osteoarthritic change observed at final follow-up., Conclusion: Middle- to long-term outcome after MPFL reconstruction with Insall's proximal realignment at our institution was evaluated, and good clinical results were observed. Most patients who did not have a severe cartilage lesion preoperatively did not develop osteoarthritic change.

Objective: The purpose of this study was to evaluate cartilage defect at medial femoral condyle on MRI in early osteoarthritis and to compare with early osteoarthritis with meniscal tear without clear cartilage defect., Materials and Methods: Twelve patients with medial pain of the knee and cartilage defect without meniscal tear by MRI were studied for cartilage defect. There were two males and 10 females with cartilage defect, and they were between 42 and 61 years of age (average, 51.6). Fifteen patients with medial pain of the knee and meniscal tear and without clear cartilage defect had been studied as meniscal tear cases. There were five males and 10 females with meniscal tear, and they were between 45 and 61 years of age (average 54.5). In both groups, knee injuries by trauma and Kellgren radiographic grade III and IV osteoarthritis were excluded. We compared cartilage defect cases and meniscal tear cases by gender, age, medial meniscus displacement ratio from the edge of the tibial medial joint surface, femorotibial angle (FTA) and Mikulicz line. We measured medial meniscus displacement ratio by the proportion of medial meniscus lesion protruding from the edge of tibial medial joint surface to all the medial meniscus width on MRI. For the evaluation of Mikulicz line, we measured the score by the length from tibial medial joint surface to Mikulicz line to tibial plateau width. chi(2) Test was used for gender, and Mann-Whitney U test was used for age, medial meniscus displacement ratio, FTA and Mikulicz line., Results: Statistically significant difference was not observed between cartilage defect cases and meniscal tear cases for age and gender. Medial meniscus displacement ratio was 13+/-12.3% in cartilage defect cases and 50.4+/-20.1% in meniscal tear cases. Medial meniscus displacement ratio in cartilage defect cases was significantly smaller than in meniscal tear cases (P=.0001). FTA was 174.9+/-2.2 degrees in cartilage defect cases and 178.3+/-4.8 degrees in meniscal tear cases. FTA in cartilage defect cases was significantly smaller than in meniscal tear cases (P=.00390). The score by the length from tibial medial joint surface to Mikulicz line to tibial plateau width was 35.8+/-11.8% in cartilage defect cases and 21.7+/-15.8% in meniscal tear cases. Mikulicz line in cartilage defect cases passes more laterally than in meniscal tear cases significantly (P=.0264)., Conclusion: In this study, we reported cartilage defect cases at medial femoral condyle in the early osteoarthritis of the knee. We think that these cases were different from early osteoarthritis with meniscal tear in alignment of lower limb and onset mechanism. It is necessary to evaluate meniscus and cartilage in MRI when we diagnose middle-aged patients with medial pain of the knee and without remarkable changes of X-ray.

Using magnetic resonance imaging (MRI), we evaluated 42 reconstructed anterior cruciate ligaments (ACLs) for impingement on corresponding posterior cruciate ligaments (PCLs) in the knee-extended position. Thirty-one single-bundle ACL reconstructions and 11 double-bundle ACL reconstructions were performed. MR examinations were performed at 3 and 12 months after arthroscopic ACL reconstructions. Using oblique axial MRIs of reconstructed ACLs, we evaluated the shape of the PCL and divided them into two groups: an impingement-positive group and an impingement-negative group. Using sagittal images, we measured the PCL index (Liu's method) and examined the correlation between the degree of impingement and the index. At 3 months after surgery, 14 of 31 single-bundle ACL reconstructions and 5 of 11 double-bundle ACL reconstructions were regarded as positive impingement on PCLs. At 12 months after surgery, 17 of 31 single-bundle ACL reconstructions and 5 of 11 double-bundle ACL reconstructions were regarded as positive impingement on PCLs. At 3 months in single-bundle reconstructions and at 3 and 12 months in all reconstructions, the PCL index of the impingement-positive group was significantly lower than that of the negative group. This study indicated that reconstructed ACLs in the impingement-positive group pressed the PCLs more posteriorly than did the impingement-negative group.

The purpose of this study was to examine the long-term clinical results of meniscus transplantation for articular cartilage defects in the knee joint. The type of study was case series. From October 1990 to June 1995, eight cases underwent allogenic or autogenic meniscus transplantations for articular cartilage defects, and seven cases were available for follow-up evaluations. The age at surgery ranged from 14 to 42 years of age (average 22.5). In one case, transplantation of tissue-engineered cartilage was performed due to pain 5 years after surgery. The other six cases were followed up for 8-13 years (average 10.1). The size of the cartilage defect ranged from 1.0 to 6.3 cm2 (average 2.8 cm2). Patients were evaluated with the Lysholm score and MR images. We also performed arthroscopic examinations in three cases at the final evaluation. This study leads to the conclusion that meniscus transplantation for articular cartilage damage is not comparable to autologous chondrocyte transplantation. Two cases showed a good clinical outcome but the tissue remained as fibrocartilage tissue in the long-term.

Objective: The purpose of this study was to evaluate the relationship between the shape of tibial spurs on plain X-rays and the meniscal changes on magnetic resonance imaging (MRI) in early osteoarthritis of the knee., Materials and Methods: Sixty-three patients (age range, 40 to 59 years; average, 51.8) underwent X-ray and MRI examinations of their knees. Ligament injuries caused by trauma and Kellgren Radiographic Grades III and IV on X-ray were excluded. The shapes of the medial and lateral tibial spurs on X-ray were classified into four types: (a) normal type; (b) horizontal type, in which the spur protruded horizontally; (c) upward type, in which the spur protruded upward; and (d) downward type, in which the spur protruded downward. The femorotibial angle (FTA) on the X-rays was also measured. The medial and lateral meniscal displacement rates on MRI were measured by the proportion by which the meniscal lesion protruded from the edge of the tibial joint surface to the overall meniscal width. The medial and lateral meniscal signal changes on MRI were classified into three types: (a) normal type; (b) intrameniscal type, which showed a high signal within the meniscus; and (c) tear type, which showed a high signal extending to the tibial joint surface. The relationships between the shape of the medial and lateral tibial spur classification on X-ray, the medial and lateral meniscal displacement rates on MRI, the medial and lateral meniscal signal changes on MRI and the FTA were evaluated statistically., Results: Statistically significant correlations were observed between the medial tibial spur classification on X-ray, the medial meniscal displacement rate on MRI and the medial meniscal signal change classification on MRI. In the downward type of medial tibial spur, the medial meniscal displacement rate (50.46+/-17.95%) and the percentage (8 out of 8 cases; 100%) involving the tear type of medial meniscus were greater than the other types. Statistical significance was not observed among the lateral tibial spur classification on X-ray, the lateral meniscal displacement rate on MRI and the lateral meniscal signal change classification on MRI. However, in the horizontal type of lateral tibial spur, the percentage (7 out of 10 cases; 70%) involving the tear type of lateral meniscus was greater than the other types. Correlations tended to be observed between the medial meniscal displacement rate on MRI and the FTA., Conclusions: In this study, there was a relationship between the shape of the tibial spur on X-ray and the meniscal changes on MRI in early osteoarthritis of the knee. The shape of the medial tibial spur on X-ray can be a useful indicator for predicting the progression of osteoarthritis of the knee. A downward type of medial tibial spur classification on X-ray may be a risk factor for developing severe osteoarthritis of the knee.

The purpose of this study was to examine the relationship between osteochondritis dissecans (OCD) of the lateral femoral condyle and lateral menisci. From 1993 to 2002, 38 knees (28 patients) were diagnosed with OCD of the lateral femoral condyle. OCD locations were graded by the Cahill and Berg classification. The types of lateral menisci were classified by Watanabe's classification. The relationship between OCD of the lateral femoral condyle and lateral menisci was examined. On the anterior-posterior view, 25 OCDs were located in zone 4 and 13 in zone 5. The types of lateral menisci were complete discoid in 19 knees, incomplete discoid in 15, and normal in 4. Ten of the 19 complete discoid menisci were damaged. Complete discoid menisci without tears were found in OCDs located in zone 4; incomplete discoid menisci were found in OCDs located in zone 5. The authors found a relationship between the type of OCD and the state of the lateral meniscus.

The management of patellar dislocation syndrome has traditionally been difficult. There are no golden standard methods for patellar dislocations probably due to the many etiologies. However, it is known that medial patellofemoral ligament (MPFL) is damaged when the patella is dislocated. The purpose of this study is to examine whether our method of MPFL reconstruction is useful for the treatment of dislocated patellae and unstable patellae. Forty-six knees (43 patients) of 68 knees (65 patients) that were operated on using our surgical procedure for MPFL reconstruction with the advancement of the vastus medialis or the MPFL reconstruction with Insall's procedure were followed up for at least 5 years. The patient age ranged from 6 to 43 years. These knees consisted of six habitual dislocation patellae, twenty-six recurrent dislocation patellae, ten traumatic dislocation patellae, and four unstable patellae. The patients were evaluated pre-operatively and more than three times post-operatively at 6, 12, 36, 60, or 120 months. No patient experienced patellar dislocation after surgery. Their post-operative Kujala's scores were significantly improved. On conventional X-ray and on stress X-ray evaluations, the mean values for congruence angle, tilting angle, lateral shift ratio, medial stress shift ratio, and lateral stress shift ratio at the final follow-up (60 or 120 months) were demonstrated to be within the normal range. We conclude that our MPFL reconstruction method with the advancement of the vastus medialis or with Insall's procedure might be recommended for the treatment of habitual, recurrent, and indeed any other type of patellar dislocation, as well as for unstable patellae.

We report two cases of mucoid degeneration of the anterior cruciate ligament (ACL). Mucoid degeneration of the ACL is a very rare cause of knee pain. There have been only seven reported cases of mucoid degeneration of the ACL in the English literature. We reviewed previous reports and summarized clinical features and symptoms, including those found in our two cases. MRI is the most useful tool for differentiating mucoid degeneration of the ACL from an intraligamentous ganglion or other lesions in the knee joint. If this disease is considered preoperatively, it can be diagnosed easily based on characteristic findings.

Objective: The purpose of this study was to evaluate anterior cruciate ligament (ACL) impingement against the posterior cruciate ligament (PCL) with the knee in an extended position, which arthroscopy cannot detect., Materials and Methods: Ten normal knees and 30 ACL-reconstructed knees were assessed using MR imaging. The three-dimensional reconstruction of the ACL, PCL, femur and tibia were carried out using commercially available three-dimensional reconstruction software. Anterior cruciate ligament impingement against the PCL was graded into three categories: Grade 1, some space between the ligaments; Grade 2, no space between the ligaments, and the reconstructed ACL ran straight; and Grade 3, the reconstructed ACL did not run straight. The angle of the reconstructed ACL against the tibial plateau was also measured., Results: All normal knees were classified as Grade 1. The 30 reconstructed knees were classified as follows: Grade 1, 12 cases; Grade 2, 7 cases; and Grade 3, 11 cases. The mean angle of the Grade 3 reconstructed ACL knees was significantly more vertical against the tibia as compared with the Grade 1 knees (P<.05). The postoperative KT-2000 side-to-side difference of the Grade 3 knees (2.8+/-4.5 mm) was larger than that of the Grade 1 knees (0.2+/-1.7 mm) and Grade 2 knees (-0.6+/-2.2 mm), but no statistically significant difference could be detected between the three groups in the postoperative KT-2000 data., Conclusion: This method is useful to evaluate ACL impingement against PCL, which cannot be detected by conventional arthroscopy during the operation. The surgeon should pay careful attention to the coronal angle of the reconstructed ACL.

Meniscal healing is well known to be region-specific, and this is thought to be mainly due to its specific vascularity. The purpose of this study was to assess regional differences in the intrinsic healing potential of the meniscus, using an organ culture model to eliminate the influence of microvasculature and the synovium. A full-thickness circular defect, 1.5 mm in diameter, was created in the inner avascular zone in meniscal explants from rabbits. As a control, a column of 1.5 mm in diameter was removed then replanted in the area where it had been obtained (Group C). In the experimental group, a 1.5 mm-diameter meniscal graft obtained from the peripheral zone of the same specimen was implanted in the damaged area (Group T). These meniscal explants were cultured for 2, 4 or 6 weeks, and the relationship between the recipient tissue and the graft was examined using both gross and histological semiquantitative scoring. The 6-week gross-examination showed that the openings were more apparent in Group C, and the score of Group T was significantly higher than that of Group C (P=0.0152). Histologically, the healing responses after both 4 and 6 weeks of incubation were significantly better in Group T than in Group C (P=0.0237, 0.0281). These results using organ culture demonstrate that intrinsic healing potential differs even without the influence of vascular supply and the synovium, indicating that the superior healing potential in the peripheral zone may contribute to the good meniscal healing in this location.

Objective: To evaluate the actual date of the return to activity and its impact on the postsurgical stability of anterior cruciate ligament reconstruction (ACLR) using hamstring grafts., Design: A retrospective analysis. The time of return to activity was determined by a questionnaire at 24 to 36 months after ACLRs., Setting: An orthopedic center., Participants: Fifty consecutive patients who had ACLRs using hamstring grafts 24 to 36 months earlier., Interventions: Not applicable. Main outcome measure The time of return to activity from a questionnaire and serial KT-2000 data at 3, 6, 12, 18, and 24 months postsurgery., Results: Patients were divided into 2 groups according to their KT-2000 side-to-side difference at 12, 18, and 24 months postsurgery. Group I consisted of patients whose differences were 3mm or less. Group II consisted of patients whose differences were more than 3mm. At 12 and 18 months postsurgery, significant differences were detected for the time of return to running and full-speed running. A multiple regression analysis for postsurgical stability at 24 months and the time of return to these 5 activities indicated that the time of return to full-speed running and sports activities had an effect on ACL stability., Conclusions: An early return to vigorous activities is not recommended in patients undergoing ACLRs with hamstring grafts.

We analyzed the mechanical and histological variables after the attachment of an autogenous tendon graft to cortical or cancellous bone. We reconstructed the medial collateral ligament of the knee in 33 Japanese white rabbits, using a bone socket procedure. The floor of the bone socket was cortical bone in group A and cancellous bone in group B. Mechanically, the pull-out test showed a tendency towards an increase in maximum failure load, with 10.9 N, 35 N and 37 N in group A, and 11 N, 18 N and 36 N in group B at 2, 4 (statistically significant difference) and 8 weeks after surgery, respectively. Histologically, the attachments were immature at 2 weeks. At 4 weeks, granulations had matured and Sharpey's fiber-like structures were seen. These fibers were more abundant in group A than in group B. At 8 weeks, the attachments in both groups were rather like the normal 4-zone structure. With time, tendon attachments matured in both groups. Our study showed that reattachment of tendons to cortical bone may be bettter than to cancellous bone.

To evaluate the spontaneous healing capability of acute anterior cruciate ligament (ACL) injuries, conservative treatment was applied in a selected group of 31 patients, who had low athletic demands. Each patient demonstrated a continuous ACL on magnetic resonance imaging (MRI), from the original femoral attachment through the tibial attachment, and an area of high intensity was detected in the substance of the ACL. The injured knees were treated using an extension block soft brace without anterior stabilization for 2-3 months. KT-2000 and MRI examinations were carried out regularly during the follow-up. Twenty-three knees (74%) were revealed to be stable in the follow-up examination, with an average of 16.1 months elapsing since the initial injuries. The KT-2000 side-to-side differences of 20 knees were less than 3 mm, and those of the other 3 knees were more than 3 mm but less than 5 mm. MRI confirmed that 21 injured ACL out of 23 knees maintained a femoral to tibial attachment and showed gradual reductions in image intensity. The positions of the other 2 injured ACL femoral attachments were different from the original femoral attachment: one was attached to the posterior cruciate ligament, and the other was located at the lateral femoral condyle anterior to the original femoral attachment. Eight knees (26%) subsequently required ACL reconstructions due to instability. This study indicates that an acutely injured ACL has healing capability. It also suggests that conservative management of the acute ACL injury can yield satisfactory results in a group of individuals who have low athletic demands and continuous ACL on MRI, provided the patients are willing to accept the slight risk of late ACL reconstruction and meniscal injury.

A new artificial loop ligament (LL) without mechanical weak points, such as a knot, has been developed to connect the EndoButton and hamstring tendons for anterior or posterior cruciate ligament (CL) reconstruction. This study assessed the mechanical properties of the LL and sutures (No. 5 Ethibond thread, EndoButton tape) and those of the different CL constructs with these materials and fixation devices commonly used in CL reconstruction. The LL had a significantly higher ultimate tensile load (UTL) and stiffness value (p < 0.001) than No. 5 Ethibond thread or EndoButton tape in static and fatigue tests (50--500 N, 1.08 million cycles). The LL-tendons-Leeds-Keio artificial ligament-staple construct complex also had significantly higher UTL and stiffness value than the Ethibond loops or EndoButton tape loop-tendons-Ethibond sutures-postscrew-fixed construct complex. Furthermore, the LL construct complex elongated the least after cyclic loading (50--150 N, 90,000 cycles). These findings suggested that using the LL construct complex might avoid a bungee cord effect and elongation before biological healing between the construct and bony socket. The LL construct complex could be a safe substitute for use during the postoperative period., (Copyright 2002 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 63: 173--181, 2002; DOI 10.002/jbm.10125)

We studied 16 women 21-23 years old with regular menstrual cycles (28+/-4 days) and no history of knee injury. From their basal body temperatures and the serum concentrations of estradiol and progesterone, the follicular, ovulatory, and luteal phases were delineated. Using a KT-2000 arthrometer, anterior displacement at 89 N and 134 N and anterior terminal stiffness (N/mm) at 134 N were measured two or three times every week over a 4-week period. Eight men 21-23 years old were also measured. In women the anterior displacement at 89 N varied between the follicular and the ovulatory phase and between the follicular and the luteal phase ( P<0.05) and at 134 N between the follicular and the luteal phase ( P<0.05). There were no statistical differences in the anterior displacement with time in men, nor in anterior terminal stiffness in either sex. We conclude that anterior cruciate ligament laxity in women might be dependent on the concentrations of hormones.

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.

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.

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.

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.

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.

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.

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.

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.