Introduction

We perform PAO via a modified Smith-Petersen approach. The purpose of this study was to investigate the result of PAO via a modified Smith-Petersen approach at a minimum 10-years' follow-up.

Aims

Acetabular dysplasia is frequently associated with intra-articular pathology such as labral tears, but whether labral tears should be treated at the time of periacetabular osteotomy (PAO) remains controversial. The purpose of this study was to compare the clinical outcomes and radiographic corrections of PAO for acetabular dysplasia between patients with and without labral tears pre-operatively.

Several radiological methods of measuring anteversion of the acetabular component after total hip replacement (THR) have been described. These studies used different definitions and reference planes to compare methods, allowing for misinterpretation of the results. We compared the reliability and accuracy of five current methods using plain radiographs (those of Lewinnek, Widmer, Liaw, Pradhan, and Woo and Morrey) with CT measurements, using the same definition and reference plane. We retrospectively studied the plain radiographs and CT scans in 84 hips of 84 patients who underwent primary THR. Intra- and inter-observer reliability were high for the measurement of inclination and anteversion with all methods on plain radiographs and CT scans. The measurements of inclination on plain radiographs were similar to the measurements using CT (p = 0.043). The mean difference between CT measurements was 0.6° (-5.9° to 6.8°).

Measurements using Widmer’s method were the most similar to those using CT (p = 0.088), with a mean difference between CT measurements of -0.9° (-10.4° to 9.1°), whereas the other four methods differed significantly from those using CT (p < 0.001).

This study has shown that Widmer’s method is the best for evaluating the anteversion of the acetabular component on plain radiographs.

Cite this article: Bone Joint J 2014; 96-B:597–603.

The Mayo-Stem is short and tapered in the anteroposterior and mediolateral directions, designed to enhance early fixation through multiple point contact in the proximal medullary cavity. The purpose of this study was to investigate the clinical and radiographic results of total hip arthroplasty (THA) using this short stem in younger patients.

A total of 97 cementless THAs using this short stem were investigated. The length of the stem used ranged from 90mm to 110 mm. The average age of the patients at the time of surgery was 50.9 years (33–64 years). The average follow-up period was 64 months (38–108 months).

The Harris hip score was used for clinical evaluation. The valgus angles of the stems and the changes in radiographic findings around the stems after surgery were investigated on the AP radiographs of hip.

The average Harris hip score was 52.0 points pre-operatively and 93.9 points at the latest follow-up. An intraoperative femoral fissure fracture of the proximal femur occurred in 15 hips (15.4%), which were treated by circlage wires. The average valgus angle of the stem was 3.5° (range: −6°–18°). The development of bone trabeculae was seen around the curve of the stem (Gruen zones 3 and 5) in 79.4 % of hips one year after surgery. A radiolucent line was found on the lateral side of the stem (Gruen zones 1, 2, and 3) in 13.4 % of hips, which occurred in connection with the development of bone trabeculae. Subsidence of the stems (> 2mm) was seen in three hips in which intraoperative femoral fissure fracture had not occurred. These hips did not get the development of bone trabeculae. In two hips of the three hips, the valgus angles of the stems were 15° and 17° respectively. In the case of the third hip, the stem was small to the proximal femur.

Overall the clinical result of THA using a short-stem was basically gratifying.

The development of bone trabeculae, the stem size to the proximal femur and the stem position were important factors for the fixation of stem. Intraoperative fissure fracture treated by circlage wires and radiolucent lines with the development of bone trabeculae did not affect the fixation of stem.

Dysfunction of acetabular dysplasia is a complex problem which includes excessive stresses on the cartilage, dynamic instability and muscular fatigue eventually leading to degenerative osteoarthrosis if left uncorrected. The most physiologic solution for a young adult with this problem is to redirect the acetabulum into a normal position. Rotational acetabular osteotomy developed in Japan aims to transfer the position of the acetabulum en bloc by circumacetabular osteotomy using the curved osteotome. Because of same curvatures of osteotomy surfaces, this osteotomy produces the greater contact among bony surfaces, stable fixation and early solid union. However, this osteotomy requires abductors splitting, leaves acetabular teardrop in its original position, and has the risk of postoperative avascular necrosis of the transferred acetabulum. Bernese periacetabular osteotomy developed by Ganz also provides good coverage of the femoral head by redirecting the acetabulum. This osteotomy preserves the vascular supply of the transferred acetabulum and allows medialization of the hip joint. On the other hand, it poses the risk of considerable morbidities due to extensive exposure, and major and/or moderate complications, such as bleeding complications, reflex sympathetic dystrophy, motor nerve palsy and heterotopic ossification are reported. In order to reduce these disadvantages, we developed a curved periacetabular osteotomy (CPO), for the treatment of hip dysplasias and have performed CPO on more than 400 hips since 1995. Both an imaging of the margin of the hip presumed to be on the quadrilateral surface and a sophisticated operative technique are needed for CPO. However, the extent of soft tissue dissection is limited with abductors left intact, and the osteotomy surfaces retain their original curvature. There have been no major or moderate complications. These advantages seem to reduce postoperative complications and promote early postoperative rehabilitation.

Recently, we compared surgical invasion and complications in patients aged over 40 years who underwent CPO (n=30) or total hip arthroplasty (THA; n=30) using postoperative levels of interleukin (IL)-6 and C-reactive protein (CRP). The mean IL-6 levels were 55.4 pg/ml and 89.5 in the CPO and THA groups, respectively (p< 0.001). The mean CRP levels were 4.5 mg/dl and 5.8 in the CPO and THA groups, respectively (p< 0.01). No major or moderate complications were encountered in either group. CPO appears to be a less invasive and safer surgical procedure for middle-aged patients than THA.

We compared the dynamic instability of 25 dysplastic hips in 25 patients using triaxial accelerometry before and one year after periacetabular osteotomy. We also evaluated the hips clinically using the Harris hip score and assessed acetabular orientation by radiography before surgery and after one year. The mean overall magnitude of acceleration was significantly reduced from 2.30 m/s² (sd 0.57) before operation to 1.55 m/s² (sd 0.31) afterwards. The mean Harris hip score improved from 78.08 (47 to 96) to 95.36 points (88 to 100). The radiographic parameters all showed significant improvements.

This study suggests that periacetabular osteotomy provides pain relief, improves acetabular cover and reduces the dynamic instability in patients with dysplastic hips.

The reduced stability of hydroxyapatite (HA)-coated implants in osteopenic conditions is considered to be a major problem. We therefore developed a model of a boosted cementless implantation in osteopenic rats.

Twelve-week-old rats were either ovariectomised (OVX) or sham-operated (SO), and after 24 weeks plain or HA-coated implants were inserted. They were treated with either a prostaglandin EP4 receptor agonist (ONO-4819) or saline for one month.

The EP4 agonist considerably improved the osteoporosis in the OVX group. Ultrastructural analysis and mechanical testing showed an improvement in the implant-bone attachment in the HA-coated implants, which was further enhanced by the EP4 agonist. Although the stability of the HA-coated implants in the saline-treated OVX rats was less than in the SO normal rats, the administration of the EP4 agonist significantly compensated for this shortage. Our results showed that the osteogenic effect of the EP4 agonist augmented the osteoconductivity of HA and significantly improved the stability of the implant-bone attachment in the osteoporotic rat model.

The existing methods of assessing limb lengthening during total hip arthroplasty (THA) are prone to error because the measurements are not parallel to the limb lengthening axis. In order to address this, we designed a caliper to estimate limb lengthening during THA and evaluated its accuracy compared with our previous device, the straight caliper. Limb lengths were measured in 100 patients. The L-shaped caliper was used in 50 cases and the straight caliper in 50. The correlation between intra-operative and post-operative radiographic measurements was significantly improved using the L-shaped device (p < 0.0001, r = 0.934). This method was extremely accurate in predicting changes in limb length due to surgery.

Introduction: To ascertain the optimal functional abductor moment arm of the hip for THA, we focused on the Trendelenburg sign. We investigate the various conditions associated with abductor moment arm to achieve a negative Trendelenburg sign postoperatively.

Methods: We reviewed 30 patients (34 uncemented primary THAs; mean age, 56 years) at a minimum of two years postoperatively. The tilting angle of the pelvis while performing the Trendelenburg test (Trendelenburg angle) was measured using a magnetic sensor system. On the hip radiographs, the %FO was calculated by dividing the femoral offset, by the distance between the centers of the bilateral femoral heads, and by multiplying by 100.

Results: The Trendelenburg angle averaged −4.3 degrees (−9 to −2.0) in all cases with a positive Trendelenburg sign, whereas it averaged +1.4 degrees (−2.0 to +12.0) when the Trendelenburg sign was negative. The %FO having a positive Trendelenburg sign (16.9 %; 10.0 to 22.5) were significantly shorter than those having a negative Trendelenburg sign (19.4 %; 13.5 to 24.7). The Trendelenburg angle correlated positively with %FO. Of the cases with a %FO value of more than 20%, about eighty percent of the cases had a negative Trendelenburg sign.

Discussion: The optimum abductor moment-arm, when the Trendelenburg sign is negative, has not been described. This study indicates that a %FO of 20 % may be one of the factors taken into account when determining the suitable size and position for acetabular and femoral neck components.

There are many previous reports dealing with the relationship between the abductor moment arm or femoral offset (FO), and other factors such as the abductor muscle strength after total hip arthroplasty (THA). Moreover, there have been no studies involving quantitative examination of the influence of posterolateral reconstruction on abductor muscle strength and FO. This study was to evaluate posterolateral reconstruction including posterior capsule, piriformis tendon and external rotators in THA and the relationship among the posterolateral reconstruction, abductor muscle strength, and FO.

We arbitrarily selected 48 limbs of 24 patients who underwent unilateral THA using a posterolateral approach. In 16 patients (12 women and 4 men; mean age, 66.8 years; range 50 to 82 years), posterolateral reconstruction was not performed (non- reconstruction group). In eight patients (6 women and 2 men; mean age, 61.6 years; range 52 to 72 years), posterolateral reconstruction was performed (reconstruction group). None of the selected cases were revision cases, cases in which the patient showed marked acetabular dysplasia, or cases involving the osteotomy of the greater trochanter. We compared these two groups. FO was measured on standard antero-posterior hip radiographs. Isometric abductor muscle (N) was measured with hand-held dynamometer. Each muscle strength was converted into a ratio of force to body weight (N/kg), and this ratio was used for comparison.

The reconstruction group showed higher value than the non-reconstruction group on the abductor muscle strength (p< 0.05). The correlation was recognised in the reconstruction group between abductor muscle strength and FO (p< 0.01 r=0.68).

There have been no studies involving quantitative examination of the influence of posterolateral reconstruction on abductor muscle strength and FO. Our results suggested that posterolateral reconstruction and appropriate reconstruction of FO were important in order to obtain the improvement on the abductor muscle strength after THA.

We performed curettage and bone grafting of amyloid cysts of the femoral neck in five patients on long-term haemodialysis. All had had hip pain on weight-bearing. The duration of haemodialysis before the operation averaged 15 years and the average age of the patients was 53 years. All the large cystic lesions were located in the anterosuperior quadrant of the femoral neck. At operation, they were found to consist of fibrous tissue containing amyloid deposits. Postoperatively, all five patients had painless hips and the grafts had incorporated into the bone defects.

We retrospectively reviewed 17 hip arthroplasties in 15 patients having haemodialysis for chronic renal failure. The duration of haemodialysis before the operation averaged 8.6 years and the average age of the patients was 61 years. All patients were followed for more than two years (mean 4.6 years). Six arthroplasties in four patients had failed due to loosening, and one of these patients died from undiagnosed infection of both hips at 7.6 years after the operation. General skeletal abnormalities caused by maintenance haemodialysis may explain the high incidence of loosening and it is important to be aware of the danger of postoperative infection. The risk-to-benefit ratio of hip arthroplasty is high in patients on haemodialysis.

We reviewed 29 patients who had developed destructive arthropathy of the spine during long-term haemodialysis. Their mean age when haemodialysis began was 43.8 years; at diagnosis they had been dialysed for an average of 8.6 years. In 26 patients, the lesions were between C4 and C7; in six they were between L4 and S1, three having lesions in both regions. Sixteen patients had had previous surgery for carpal tunnel syndrome. Spinal surgery was performed in nine patients with satisfactory results in only five. We demonstrated beta-2 microglobulin amyloid deposits in the discs and surrounding ligaments in all biopsied cases. The natural history and management of this condition are not yet clear.