In order to more critically evaluate the function of ACL-deficient knees, we designed a functional ability test composed of four different one-leg hopping performance tests. The functional tests utilized in this study were: 1. figure of eight hop; 2. one-leg up/down hop; 3. one-leg side hop; and 4. one-leg hop for distance. Sixty-six athletes who underwent ACL reconstruction were evaluated with these performance tests. When compared with athletes with ACL deficiency, those who had ACL reconstruction showed significant improvement in all the tests. On the other hand, only 39% of the subjects were judged to be normal in all four performance tests despite the surgical treatment. The athletes who were apprehensive about performing these functional tests showed poor results regardless of actual stability and muscle strength.

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There are many factors influencing postoperative knee stability after anterior cruciate ligament (ACL) reconstruction. In this study, postoperative knee stability was measured and factors influencing the values are discussed. Anterior laxity of the knee in 163 patients, who underwent unilateral ACL reconstruction under arthroscopic control, was measured at 18 or 24 months postoperatively. There were 78 males and 85 females with a mean age of 22 years. Freshfrozen allogeneic tendon (N=65), autogenous bone-patellar-bone tendon (N= 57), or autogenous medial hamstring tendons (N=41) were used for the graft. Instrumented drawer tests in the Lachmen position were performed to measure anterior tibial displacement at 200 N (anterior laxity) . Side-to-side difference (reconstructed minus normal) in anterior laxity (ADL) was used as an indicator of adnormal laxity. ADL was 1.5 ± 2.5 mm. Age, the interval from the time of initial injury to the operation, and meniscal operation had no effect on the the ALD values. ALDs for males and females were 1.4 ± 2.5 and 1.7 ± 2.5 mm, respectively. There was no statistical significant difference. ALDs of allograft, autogenous patellar tendon and medial hamstring tendons were 1.1 ± 2.1, 1.4 ± 2.9 and 2.1 ± 2.6 mm, respectively. One-way ANOVA demonstrated that there was a statistically signi-ficant difference in ALD between allograft patients and patellar tendon graft patients (p<0.05) . Since the allograft and multiplied medial hamstring tendons are cylindrical in shape and have a diameter of more than 8 mm, the results were better compared to autogenous patellar tendon.

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Multivariate analyses were performed, first, to clarify the relationship between postoperative anterior laxity and postoperative quadriceps muscle strength; second, to elucidate the effects of these two parameters on results, evaluated with the Lysholm score; and, third, to ascertain preoperative or intraoperative factors that affect postoperative anterior laxity or postoperative quadriceps muscle strength. Subjects were 123 patients who underwent ACL reconstruction using the hamstring tendons in their unilateral knee since 1989. Age ranged from 13 to 53 years, and the postoperative follow-up period ranged from 2 to 5 years. Patients underwent identical surgery and postoperative management. There was no correlation between postoperative anterior laxity and postoperative quadriceps muscle strength (r=0.03) . These results show that these two parameters are independent of each other. Postoperative anterior laxity significantly affected results, which were evaluated with the Lysholm score (p=0.03), although postoperative quadriceps muscle strength had no significant effect on the results (p=0.23) . Among possible factors that might affect postoperative anterior laxity, the multivariate analysis demonstrated that initial graft tension applied during surgery and age at the time of operation significantly affected postoperative anterior laxity. Namely, postoperative anterior laxity was low when the initial graft tension was high, and in cases of advanced age. On the other hand, only preoperative sports level significantly affected postoperative quadriceps muscle strength. That is, when the preoperative sports level was high, postoperative muscle strength was great.

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Although total hip arthroplasty (THA) achieved excellent clinical outcome for patients with osteoarthritis of the hip, there is still controversy about its long-term durability in middle-aged patients. We investigated 97 cases of patients aged from 40 to 59 years who received one of three types of arthroplasty: THA, bipolar hemiarthroplasty (BHA), or surface replacement (SR) . The clinical outcome in SR was poor and the survival rate at 10 years was less than 30%. Although migration of implants was common in BHA, there was no difference in the survival rate between BHA and THA.

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A series of 193 hips treated with total hip arthroplasty in patients who were less than 59 years of age was reviewed. Satisfactory clinical results were obtained in most of the cases at the time of the last follow-up. Aseptic loosening of the components was observed in 57 hips (29.5%) and revision surgery was performed in 38 hips (19.7%) . Second revision surgery was performed in 6 hips. Relatively good clinical results were obtained in all these cases after revisions and second revisions. Technical failures including cementing techniques and selection of components seemed to be the main cause of aseptic loosening of the components rather than the relatively young age of the patients. These results support the premise that total hip arthroplasty is one of the recommended surgical treatments for endstage osteoarthrosis of the hip in younger patients.

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To prevent the development of osteoarthritis of the hip joint in young adults, we carried out a shelf operation, femoral osteotomy and cup arthroplasty. A shelf operation was the main type of treatment. Understanding the natural course of osteoarthritis is requisite to determine effectiveness of these procedures to prevent progression of the disease. We followed clinical and radiological outcomes of 73 cases and found progression of osteoarthritis in those in which the hip joints were bilaterally affected or had severe dysplasia. We also reviewed 18 cases, patients under 30 years old, who were treated with a shelf operation, and found excellent clinical and radiological outcomes. For treatment of incongruity of the hip joint and advanced osteoarthritis in young adults, we indicated femoral osteotomy and cup arthroplasty, respectively. These procedures were conducted to preserve the bone stock and to prevent the development of osteoarthritis.

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To clarify the differences in the diagnostic rate for meniscal tearing according to patients' ages and causes, we conducted magnetic resonance imaging (MRI) in 184 knees of 175 patients. We compared the findings of arthrography, gross examination, arthroscopy, and histopathology. Arthrography in patients with meniscal tears showed 63.0% sensitivity, 89.1% specificity, and 84.9% accuracy. MRI in the same patients disclosed 82.9% sensitivity, 86.0% specificity, and 85.5% accuracy, levels nearly similar to those of arthrography. Findings by arthrography according to patients' ages revealed no difference in each age group, whereas findings by MRI showed significant decreases of brightness in patients 40 years old or over. Diminished diagnostic rates by MRI resulted from increased changes of brightness in the menisci that had been caused by histological changes such as mucoid and hyalinization. Examination, however, of patients less than 40 years old under light microscopy revealed no menisci degeneration as a cause for the changes of MRI brightness. Based on the present situation in which lateral-site medial-meniscus diagnosis is difficult, especially in middle-aged and elderly patients, it is considered necessary to combine arthrography with MRI to obtain accurate diagnoses.

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It has been thought that the underlying mechanism of thoracic outlet syndrome (TOS) was compression of the neurovascular bundle at the thoracic outlet. In recent years, however, it has been confirmed that not only compression but also stretching of the brachial plexus constitute the underlying pathophysiology of TOS. We classified TOS into compression type and stretching type using neurography of the brachial plexus and clinical findings. These types of TOS were separately managed.
Conservative treatment should be the first choice of treatment for all patients with TOS, which includes correcting the posture and strengthening the shoulder girdle muscles with an orthosis stabilizing scapula (Kumamoto University scapular band) . Emphasis was placed on alleviation of brachial plexus irritation due to its stretching. Based on our experience, thoracic outlet decompression operation and cervical traction were contraindications for the stretching type of TOS.
We believe that the appropriate conservative treatment adapted to the different conditions, compression and stretching, leads to good results.

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We assessed the transformation of the proximal tibia after high tibial osteotomy (HTO) for osteoarthritis of the knee and subsequent total knee arthroplasty (TKA), and investigated the effects of tibia transformations on surgical procedures during TKA for high-tibial-osteotomized knee joints. The study was based on examinations of X-ray films of a study group of 3 patients with 5 TKA following HTO, and two control groups: one of 7 patients with 9 HTO, and the other of 10 patients with 15 primary TKA. Patellar height, tibial angle and tibial posterior inclination were measured. The group of patients with TKA following HTO and the HTO group showed significantly lower patellar height and tibial angle after HTO than those before HTO. Furthermore, the group of patients with TKA following HTO also showed a significantly lower patellar height and tibial angle before TKA than the primary TKA group. At the time of TKA, the patella infera and the transformation of the proximal tibia may cause difficulties in obtaining the appropriate surgical field or in setting the prosthesis.

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Eleven unicompartmental knee arthroplasties in 10 patients who had continued to have progressive medial compartmental osteoarthritis after a high tibial osteotomy were evaluated retrospectively. The age at osteotomy was 63 years and the average interval between osteotomy and arthroplasty was 6.6 years (range : 1.5-17.5) . The average length of follow-up after arthroplasty was 6.4 years. The knee score of the Japanese Orthopaedic Association was 56 points at osteotomy, 56 points at arthroplasty, and 75 points at the final follow-up. Limb alignment was investigated with the standing femoro-tibial angle. Angulation averaged 185 degrees at osteotomy, 183 degrees at arthroplasty, and 178 degrees at follow-up. Radiographic examination showed that one patient had loosening of the tibial component, but no other loosening was identified. Radiographic progress of osteoarthritis was seen in 9 of 11 knees at the time of arthroplasty. Compared with the procedures for total knee arthroplasty, those for unicompartmental arthroplasty were notably easier to perform even in knees after a failed tibial osteotomy.

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