Rotational acetabular osteotomy (RAO) is a circumacetabular osteotomy of the acetabulum designed to correct the dysplastic hip. In this procedure, the femoral head is covered with the articular cartilage of the acetabulum and the forces of weight-bearing are distributed more evenly. The purpose of this study was to determine whether RAO is effective in delaying the onset of arthrosis in patients with painful hip dysplasia.

We determined the outcome of 20 female patients in whom RAO was performed between 1975 and 1984; all were aged 20 to 29 years at the time of surgery. The pre-operative centre-edge angle of Wiberg was 0 or negative with proximal subluxation of the femoral head. Of these, 10 were lost to follow-up before the age of 42. In these patients, however, radiographs showed no signs of arthrosis at the last follow-up. The remaining 10 patients were examined 15 to 25 years after surgery, when they were 42 to 47 years old. Radiographs revealed findings of arthrosis in only two of them who had had the secondary acetabulum before surgery.

To evaluate the efficacy of preventive medicine, it is necessary to compare the results of intervention with the natural course of the disease. Wiberg reported on the natural history of seven female patients with severe hip dysplasia in 1939. When these patients were 13 to 34 years old, radiographs demonstrated no sign of arthrosis and the centre-edge angle was equal to or less than 12 degrees with proximal subluxation of the femoral head. These hips deteriorated to advanced arthrosis by the age of 42 years. Thus the outcome of our patients was significantly better than the natural course.

In conclusion, our study suggests that RAO is effective in delaying the onset of arthrosis in patients with painful hip dysplasia.

Side shift exercise was originally described by Mehta. Since 1986, we adopted it for the treatment of idiopathic scoliosis. Outcome of the side shift exercise for the patients with idiopathic scoliosis after skeletal maturity was evaluated retrospectively. Fifty-three patients with idiopathic scoliosis whose curve was greater than 20 degrees by the Cobb’s method were included in the study. All the patients were treated only by the side shift exercise and their treatment was started after skeletal maturity. Skeletal maturity was diagnosed by Risser’s method as either grade IV or grade V. The study comprised five men and forty-eight women. Twenty-six patients had thoracic curve, eight had thoracolumbar curve, and nineteen had double major curve. Patients were instructed to shift their trunk to the concavity of the curve repetitively while they were standing and to maintain the side shift position while they were sitting. In double major curve, larger curve was the subject of the treatment. The average age at the beginning of the treatment was 16.3 years (range, 13 to 27 years), and the average age at final follow-up was 19.8 years (range, 14 to 33 years). The average follow-up period was 3.5 years (range, one to 11 years). The average Cobb angle at the beginning of the treatment was 33.3 degrees (range, 20 to 74 degrees), and the average Cobb angle at final follow-up was 32.2 degrees (range, 10 to 73 degrees). Curves of four patients decreased 10 degrees or more. Most of long term follow-up studies reported that untreated idiopathic scoliosis progressed even after skeletal maturity. Although the follow-up period was much shorter, results of the present study suggested that the side shift exercise was a useful treatment option for the management of idiopathic scoliosis after skeletal maturity.

Pin clamp motion was continuously monitored using a displacement sensor as patients walked with a dynamic fixator applied. Patients with a shaft fracture, nonunion or lengthening of the tibia were monitored, all of whom were in the stage of dynamization. The Hifixator equipped with a ball bearing mechanism on the inner surface of its dynamic pin clamp was used as a dynamic external fixator. The aim of this study was to estimate the magnitude of movement and the type of deformation occurring at the fracture site or callus generated after distraction osteogenesis. The actual motion of the bone fragment has components with six degrees of freedom, which are transferred to the pin clamp. The magnitude of the displacement of the pin clamp along the shaft is expressed by an equation involving these six components. If the pin clamp has a sufficiently smooth sliding surface and a small clearance between it and the shaft, and the pin clusters are sufficiently rigid during walking, the amount of the displacement can be expressed by the linear combination of these components.

Accuracy of the measurement was evaluated using a bone model fixed with a Hifixator mounted with a displacement sensor, by performing dynamic loading tests with axial, bending and torsional forces The measured values agreed well with the theoretical values when the rigidity of the bone model was high. The displacement was recorded versus time during more than twenty cycles of walking with weight bearing of the patients. The rhythm of walking was controlled with a metronome set at 0.5 Hz. The displacement curve had an oscillatory component synchronized with a heel strike and a toe off, a time dependent component expressed by shifting of the baseline, and an irreversible component during a non-weight bearing period after walking. The three components were analyzed with a simple Voigt model.

In all patients, both the amplitude of the oscillatory component and the time dependent component expressed as retardation time decreased as healing proceeded, and by the time of fixator removal the irreversible component had disappeared. This method was useful for quantitatively evaluation the viscoelastoplascity of the healing site.

The purpose of this study is to elucidate the possibility of an ideal joint alignment after monofocal lengthening of tibia in achondroplastic patients. In 10 cases of the alignments of knee and ankle joints of tibias in which plane radiographs were examined.Unilateral fixators were applied to both tibias,after lengthening in the normal manner, deformity was corrected manually in a single procedure without anesthesia. In order to determine the amount of angle to be corrected, a line was first drawn on the radiograph from the center of the knee joint to the center of the ankle joint. (This line is named the Knee-ankle line: KAL).

Next we drew a line along the ankle joint and measured the angle between this line and KAL. We also drew a line across the tibial plateau and measured the medial angle between this line and KAL. We tried to align the ankle joint perpendicular to KAL and the medial angle between the tibial plateau and KAL at 87 degrees , instead of trying to align the axis of the tibial shaft perfectly straight. The medial angles between the line across the tibial plateau and KAL were corrected to 86 degrees in average, with a range from 84 to 90 degrees, and the medial angles between the line across the ankle joints were corrected to 87 degrees in average, ranging from 80 to 90 degrees in result.

In conclusion, joint alignments of tibias in achondro-plastic patients were able to be corrected successfully without any complications using our monofocal lengthening technique. And severe varus deformities of tibias can be corrected even with monofocal lengthening technique by trying to correct the alignments of knee and ankle joints rather than trying to straighten tibial shafts.

Tartrate-resistant acid phosphatase is contained in multinucleated giant cells of giant cell tumour of bone (GCT) and chondroblastoma (CBL) as well as in osteo-clasts. Yet few studies have so far been done regarding serum acid phosphatase (AcP) level in patients of GCT or CBL. The purpose of this study is to elucidate the clinical significance of serum AcP as a tumour marker for GCT and CBL. Serum AcP value was examined in nine GCT patients and three CBL patients before and after surgery. In the GCT cases, serum AcP values before surgery were high in five cases. They were 14.0 IU/L, 68.7 IU/L, 45.9 IU/L, 21.9 and 31.3 IU/L (normal value; 7.1–12.6 IU/L). They decreased after surgery to 7.7 IU/L (55% of the preoperative value), 8.2 IU/L (12%), 7.8 IU/L (17%), 6.1 IU/L (28%) and 10.0 IU/L (32%), respectively. Serum AcP values before surgery were within normal limits in the remaining four GCT cases. Even in these four cases, postoperative serum AcP level was lower than the preoperative level. Postoperative/preoperative AcP ratios in these four cases were 67%, 80%, 69% and 76%. In the CBL cases, serum AcP values were high in all cases. They were 15.1 IU/L, 13.1 IU/L and 13.7 IU/L. They decreased after surgery to 10.3 IU/L (68% of the pre-operative value), 10.2 IU/L (78%) and 9.7 IU/L (71%), respectively, all within normal limits. Therefore, it is concluded that serum AcP is a useful tumour marker for GCT and CBL in diagnosing the tumour as well as in evaluating the efficacy of treatment.

Femoral lengthening has been associated with narrowing of the joint space at the hip. We have studied the joint space before lengthening in 20 patients with a short femur due to a femoral-shaft fracture (15) or distal femoral epiphyseal injury (5). Their mean age at injury was 16 years (3 to 27) and the mean shortening was 5.4 cm (1.1 to 14).

We found that the hip joint space of the shortened femur was significantly narrower (p < 0.001) than that on the normal side, with a mean narrowing ratio of 15.5% (−5 to +43). The narrowing ratio was directly related to the period spent non-weight-bearing (p < 0.001), but not to the amount of femoral shortening.

We have shown that the joint space of the hip in patients with post-traumatic femoral shortening was narrowed even before femoral lengthening had been started.