Takehiko Sugita

Radial displacement of the medial meniscus in varus osteoarthritis of the knee.

The macroscopic and histologic findings for 31 medial menisci and medial tibial plateaus obtained during total knee arthroplasty were examined to clarify the etiology and progression of varus osteoarthritis. Medial menisci were preserved fairly well in cases of severe osteoarthritis in which the medial joint space had already disappeared. The anterior segment was preserved in 26 (84%) menisci and the posterior segment was preserved in 11 (35%). The medial meniscus may have been preserved because of its radial displacement. Exposure of subchondral bone of the medial tibial plateau occurred in all 31 knees. The exposure of subchondral bone was centered in the anterior, middle, and posterior in nine, 10, and 12 medial tibial plateaus, respectively. There was a mechanical inconsistency between the pattern of preservation of the medial menisci and the location of exposure of subchondral bone on the medial tibial plateaus. The inconsistency reflects that the segment of the medial meniscus on which the excessive load was considered to exist was preserved fairly well. The authors’ hypothesis for explaining this inconsistency is that radial displacement of the medial meniscus precedes narrowing of the medial joint space during progression of varus osteoarthritis, so that the displaced meniscus is saved from severe degeneration or attrition.

Histologic Findings and Possible Causes of Osteochondritis Dissecans of the Knee

Background The histologic findings of osteochondritis dissecans of the knee vary widely, leading to differences in the interpretation of its origins. Hypothesis The differences in the histologic findings of osteochondritis dissecans might represent a course of pathologic progression. Study Design Descriptive laboratory study. Methods Twelve knees in 11 patients (average age, 16 years) with osteochondritis dissecans of the medial femoral condyle were treated by biological internal fixation. During the surgery, cylinder osteochondral plugs were taken from the center of the osteochondritis dissecans lesion and examined with light microscopy. Results A complete or partial cleft separated the specimens into 2 parts: basal and fragment sides. The surface of the basal side was covered with dense fibrous or cartilaginous tissue and active bone remodeling was found beneath the surface. In the fragment side, the deep surface was also covered with dense fibrous or cartilaginous tissue and the articular surface consisted of normal articular cartilage. The area between these 2 surfaces could be classified into 3 types: (1) necrotic subchondral trabeculae, (2) viable subchondral trabeculae, and (3) cartilage without bone trabeculae. Conclusion Based on the histologic findings of this study, the following origins and the pathologic progression of osteochondritis dissecans might be assumed: the initial change in the subchondral area is bone necrosis or subchondral fracture; the necrotic bone is then absorbed and replaced either by viable subchondral trabeculae or cartilage without bone trabeculae. Clinical Relevance The results of this histologic study provide readers with several insights about the causes and treatment options of osteochondritis dissecans.

Does estrogen alter the mechanical properties of the anterior cruciate ligament?: An experimental study in rabbits

Background It is well known that anterior cruciate ligament (ACL) injuries are commoner in female athletes. Accordingly, we hypothesized that serum estrogen may play some role in this sex difference. We evaluated the relationship between serum estrogen levels and the mechanical properties of the ACL in rabbits. Animals and methods In 40 ovariectomized rabbits, the serum estrogen levels (SEL) were controlled by intramuscular injection of 17β-estradiol. The mean SEL in each rabbit was defined as the average of 5 determinations done at 1, 2, 3, 4 and 5 weeks after ovariectomy. The animals were divided into 4 groups according to the dose of estradiol administered (low, medium, high and control: L, M, H and C, respectively) and into 2 groups according to the mean SEL (high-SEL group and low-SEL group). The medial portions of ACL attached to both femur and tibia harvested at 5 weeks after ovariectomy were examined mechanically. Results The mean serum estrogen levels in groups C, L, M and H were 37, 50, 60 and 231 pg/mL. Statistically significant differences in the mean serum estrogen levels were seen among the 4 groups, except between groups L and M. Statistically significant differences were found between groups M and H in both the ultimate tensile stress and linear stiffness. In the comparison between 2 groups using the mean SEL value, both ultimate tensile stress and linear stiffness were lower in the high-SEL group. In all animals, a positive correlation was found between ultimate tensile stress and linear stiffness. Interpretation Our findings suggest that high SEL might be one of the factors in the multifactorial pathogenesis of ACL rupture.

Cylindrical osteochondral graft for osteochondritis dissecans of the knee: A report of three cases

The treatment for osteochondral defects after separation of the fragments of osteochondritis dissecans of the knee has recently been greatly advanced using mosaicplasty or autologous chondrocyte transplantation. Ideally, the osteochondritis dissecans fragment should be fixed before the occurrence of separation or formation of loose bodies. The method of treating a patient with an osteochondritis dissecans lesion of the knee depends on whether the epiphyseal cartilage on the growth plate is open or closed. Although rest or drilling usually achieves union of the fragment in the presence of an open physis, secure internal fixation using screws, wires, or bone pegs is usually needed after growth plate closure. Unfortunately, damage to the articular cartilage can occur when using these fixation devices. In 1999, Berlet et al. reported on a patient treated with an autogenous osteochondral graft (mosaicplasty) for an unstable osteochondritis dissecans lesion of the knee. They used three 4.5-mm diameter osteochondral plugs and described their method as biologic internal fixation. Between 1995 and 1997, we treated three patients with osteochondritis dissecans using a 10-mm diameter cylindrical osteochondral graft to both internally fix and allow repair of the fragment. All three patients had closed growth plates. Our method is consistent with the concept of biologic internal fixation described by Berlet et al. In this study we report our technique and the outcomes of treatment in these three patients. SURGICAL TECHNIQUE

Traumatic separation of a type I bipartite patella: a report of four knees.

Four knees in three patients with traumatic separation of a Type I bipartite patella are reported. Sudden anterior knee pain and an audible pop occurred at the time of the injury and the patients had aching or dull pain before the traumatic episode. Previous aching or dull pain led us to differentiate this type of injury from a usual transverse fracture. A round fracture line seen on the radiographs also led us to differentiate this type of injury from a stress fracture. Accordingly, the diagnosis of a traumatic separation of a Type I bipartite patella was confirmed. This is the first report of a traumatic separation of a Type I bipartite patella to our knowledge.

Is the mechanism of traumatic posterior dislocation of the hip a brake pedal injury rather than a dashboard injury

This study proposes that the mechanism of traumatic posterior dislocation of the hip (TPDH) is a brake pedal injury rather than a dashboard injury. A total of 168 cases of TPDH were treated during the past 10 years. Clinical records of 48 patients, who were drivers and suffered from a head-on collision accident, were examined. The right hip was involved in 45 cases. A total of 31 cases were not accompanied by knee injuries. In 11 cases with foot or ankle injuries and right hip dislocation, 10 had right foot or ankle injuries. If the mechanism of TPDH was a dashboard injury, the left hip would be involved more frequently and there would be more knee injuries. Our hypothesis about the mechanism is that, in a head-on collision, the driver presses desperately on the brake pedal with his right hip slightly flexed, adducted and internally rotated.

Pigmented villonodular synovitis of the knee with lesions of the bursae.

Five patients with pigmented villonodular synovitis of the knee associated with lesions of the posterior periarticular bursae were treated by posterior exploration, excision of the bursal tissue, and routine anterior synovectomy of the knee. It was hypothesized that complete excision of the posterior periarticular bursae would reduce the high recurrence rate of pigmented villonodular synovitis of the knee. To completely excise the periarticular lesions, two posterior oblique skin incisions were used. In all patients, periarticular lesions were seen clearly on computed tomography scans after air arthrography and on magnetic resonance imaging scans. The patients were followed up for 6.9 years on average (range, 3.3–8.1 years) after surgery. One of five patients required reoperation because of recurrence. Two of five patients required manual mobilization after release of the intraarticular adhesion. However, in the remaining three patients, who started continuous passive motion exercise immediately after surgery, full range of motion was restored within 3 months after the operation. Complete excision of the periarticular lesions is recommended to reduce the high recurrence rate, and continuous passive motion exercise immediately after surgery also is recommended to prevent reduction of range of motion.

Incidence of Medial Plica in 3,889 Knee Joints in the Japanese Population

PURPOSE This study aimed to document the incidence of medial plicae (plica synovialis mediopatellaris) in a large sample of the Japanese population and classify them in a type-dependent manner. METHODS The incidence of medial plicae was investigated during arthroscopic surgery of 3,889 knee joints in 3,563 patients (mean age, 35 years); medial plicae were classified according to Sakakibaras classification (type A, a cord-like elevation in the synovial wall; type B, a shelf-like appearance; type C, a large shelf-like appearance covering the anterior surface of the medial femoral condyle; and type D, double insertions into the medial wall or having a central defect). Of all the knee joints examined, 2,006 knees belonged to male patients and 1,883 to female patients. Both knee joints were examined in 326 patients. From these data, the incidence of medial plicae was calculated. RESULTS The overall incidence rate of medial plicae was 79.9%. The incidence of Sakakibara type A, B, C, and D medial plicae was 35.2%, 22.4%, 12.3%, and 10.0%, respectively. This pattern was reflected in all age groups in both genders, except in women aged 20 to 39 years. The κ coefficient was moderate, at 0.407, in the patients in whom both knee joints were examined. CONCLUSIONS In a large cohort of Japanese patients undergoing arthroscopic knee surgery, the incidence of medial plica was 79.9%. The same pattern was seen in almost all age groups and in both genders (type A > type B > type C > type D). LEVEL OF EVIDENCE Level IV, prognostic case series.

Effect of estrogen on tissue elasticity of the ligament proper in rabbit anterior cruciate ligament: measurements using scanning acoustic microscopy

BackgroundPrevious epidemiological studies revealed that anterior cruciate ligament (ACL) injuries were more frequently seen in female athletes than in male athletes. To elucidate the pathogenetic roles of estrogen in ACL ruptures, the elasticity of ACL tissue was measured using a scanning acoustic microscope (SAM) in an estrogen-controlled animal model.MethodsA total of 40 ovariectomized Japanese white rabbits were randomly divided into four groups according to the administered dose of 17β-estradiol (groups L, M, H, and C). Injection of 17β-estradiol was performed 1, 2, 3, and 4 weeks after surgery, and doses in groups L, M, and H were 50, 100, and 500 μg/kg, respectively. Group C received no estradiol. Only groups L, M, and C were used for current analyses because their mean serum estrogen levels were within the physiological range (groups C, L, M, and H: 37, 50, 60, and 231 pg/ml, respectively). Five weeks after ovariectomy, the lateral portion of the ligament was harvested. Specimens were fixed with 10% neutralized formalin and embedded in paraffin. Then, 10 μm thick sections were cut perpendicular to the ligament fibers for routine histological staining and measurement with SAM.ResultsThe mean tissue sound speeds of groups C, L, and M were 1727 ± 32, 1683 ± 53, and 1665 ± 63 m/s, respectively. Group M presented significantly lower tissue sound speed than group C (P = 0.021). Furthermore, a negative correlation was found between the mean serum estrogen level and mean tissue sound speed of the ACL among all animals in groups C, L, and M (r = 0.47, P = 0.016).ConclusionThe results of the present study indicated that estrogen altered the tissue elasticity of rabbit ACL. Estrogen may constitute one of the pathogenetic factors in ACL rupture in female athletes.

Osteochondritis dissecans of the knee in identical twins: a report of two cases

We report the second case of osteochondritis dissecans (OCD) of the knee in identical twins (bilaterally in one and unilaterally in the other). Fixations with bio-absorbable pins, cylindrical osteochondral graft, and osteochondral mosaicplasty were all successful and bone union was achieved. We considered that genetic factors remain essential even if other factors (particularly repetitive trauma) are mainly responsible for the occurrence of OCD.