HIP International

The quality of bone encountered in the proximal femur at primary total hip arthroplasty varies considerably. It would be advantageous to improve the bone stock quality of patients who are likely to require subsequent revision. Impaction grafting with morsellised autograft was performed at primary total hip arthroplasty on seven patients who had poor proximal femoral bone stock. Minimum follow-up was 33 months. One patient died 5 weeks post-operatively. Radiographic assessment showed improved bone stock in five hips with little or no improvement in one hip. There was no evidence of prosthetic subsidence. Impaction grafting at primary total hip arthroplasty is a viable method of improving bone stock in patients with poor proximal femoral bone quality. The technique would be of particular benefit in the younger patient presenting for total hip arthroplasty with poor bone stock in the proximal femur.

The purpose of this study was to relate changes in bone mineral density post-operatively around a cemented femoral prosthesis with changes in bone turnover. This might allow appropriate timing of antiresorptive therapies in the prevention of aseptic loosening. We recruited ten patients and evaluated both bone turnover, by measurement of urinary N-telopeptide of collagen type I, bone specific alkaline phosphatase and osteocalcin, and bone mineral density following total hip arthroplasty. Bone formation markers decreased significantly postoperatively (p<0.001). Bone resorption markers increased postoperatively and were maximal at 6 weeks (p<0.05). There was a 5–15% decrease in bone mineral density at the proximal femur by 6 months (p<0.01). The changes in bone mineral density confirm the pattern of reduced stress in the proximal femur. The early decrease in bone formation markers was unexpected and could relate to enoxaparin therapy. The optimal time to administer antiresorptive therapy might be 6–12 weeks post-operatively.

To assess the role of osteoporosis and fracture comminution in the migration of the tip of the sliding screw within the femoral head, as well as the fracture collapse in anatomically reduced and adequately fixed intertrochanteric fractures, 151 patients, whose intertrochanteric fractures had been treated surgically with anatomic reduction and a centrally placed Dynamic Hip Screw (Protek Synthes, Switzerland), were reviewed with an average follow-up of 6 months after the fracture had healed (mean 9 months after fracture fixation). Osteoporosis was determined using the Singh scale, whereas fracture comminution was classified using the Tronzo criteria. Vertical and horizontal screw migration as well as fracture collapse (screw retrolisthesis) were measured in immediate anterioposterior postoperative roentgenograms and in roentgenograms at the end of the treatment. Failure in osteosynthesis occurred in 2.65% of the cases. Osteoporosis is strongly related to vertical (P = 0.00001), and horizontal (P = 0.0125) migration of the tip of the screw within the femoral head and less so to fracture collapse. On the other hand, fracture comminution is strongly related to fracture collapse (P = 0.0124) but not to the migration of the screw within the femoral head. The successful outcome of treating patients with intertrochanteric fractures depends on both adequate biology (no severe osteoporosis) and adequate mechanics (proper implant and surgical technique). Anatomic reduction and central placement of the sliding screw must be performed as a routine. Modifications to decrease the loading of the fractured hip (medial displacement and valgus osteotomy) should only be considered in exceptional cases in the presence of significant osteoporosis, thus avoiding the expected severe vertical and horizontal migration of the tip of the screw as well as fracture collapse.

Eighty Charnley low-friction arthroplasties, performed on 49 patients with juvenile chronic rheumatoid arthritis, between 1966 and 1986, were followed-up for an average duration of 217 months (18.1 years; 26 to 366 months). There were 10 male patients (17 arthroplasties) and 39 females (63 arthroplasties) whose average age at time of operation was 28.5 years (18 to 35 years). A total of 14 patients (24 arthroplasties) had died, at an average of 208 months (17.3 years, 26 to 339 months) following operation.

All patients had marked improvement in levels of pain, function and range of movement of the joint, with 88% (43 patients, 70 arthroplasties) being completely free of pain and all but one of the remainder experiencing only minimal discomfort. Fourteen acetabular components (18%) were revised at an average of 148 months (12.3 years: 26 to 252 months) from the time of operation. Three were revised for deep sepsis, four for excessive wear, and seven for aseptic loosening (9%). Three acetabular components are currently loose and the total aseptic loosening rate was therefore 13% (10 hips). The average acetabular wear rate was 0.11 millimeters per year for the entire series. Twelve femoral components were revised at an average of 153.8 months (12.8 years; 26 to 231 months), three for deep sepsis, five for aseptic loosening (6%) and three following fracture of the implant. One component was revised, although not actually loose, during an operation to replace a loose acetabular component. One of the surviving implants is currently loose and the total rate of mechanical failure of the femoral implant was therefore 11% (9 hips). Acetabular component survivorship was 94% (95% C.I.: 88 - 99%) at 10 years and 79% (69 - 89%) at 25 years, with the survivorship of the femoral implant being 95% (90 - 100%) and 81% (70 - 91%) respectively.

This is a retrospective study of one particular design of cemented hip (the 3M - Capital) used in Great Britain in the early 90's. The study included 224 primary THRs performed over a period of 5 years (average follow-up: 38.4 months) using either monobloc (31) or modular (193) stems the former made of stainless steel and the latter of titanium alloy. A high incidence of early loosening of the femoral component was noticed with both types of stem (12.5% definite loosening, 11.16% possible loosening). Possible aetiologies are discussed. Thirty-five patients (15.6%) were listed for revision. Early failure with the use of the stainless steel implants version of this prosthesis is so far unreported. Patients with early loosening were heavier than those without loosening over the same period of follow up, which was statistically significant. Histological findings at the time of revision are also discussed. In early 1998 a national audit was initiated to locate all the patients with Capital hip implant and these are the results of the study at one of these centres. The need for a national arthroplasty register in a country where more than 40,000 hip replacements are performed annually has become more obvious with failure of the Capital hip.

Sixty eight cementless acetabular revisions were performed using impacted morsellized bone graft and the Harris Galante 1 porous coated component (HGP 1). Acetabular defects were graded according to the American Association of Orthopaedic Surgeons classification. Twenty nine (43%) were contained (Type 2 cavitatory) and thirty nine (57%) uncontained (Types 1 or 3 - segmental or combined) defects. The patients were followed prospectively for a mean of five years (range two to ten years). Radiological evidence of graft remodelling was seen in twenty two hips. Progressive radiolucent lines were present in eight cases (12%). Two screws broke. There were two cases of deep infection. Radiological failure, with a change in cup angle of greater than 5 degrees or migration of greater than 5 mm, was seen in six cases (9%). All six had uncontained defects (segmental or combined). Gratifying medium term results have been obtained after reconstruction of contained acetabular defects using impacted morsellized bone graft and the cementless HGP 1 cup. Inadequate graft support in uncontained defects resulted in six cases of failure.

The authors experienced two cases of alumina prosthetic components fracture among the 2879 implanted in 10 years; these components were part of 1484 prosthetic implants. In both cases ceramic fracture was the result of a surgical technical error: in the first case a 32 mm alumina head was replaced in the same tapered neck with a 28 mm one during cup revision without removing the stem; after 9 months the new head failed. In the second case the prosthesis presented recurrent sub-dislocations causing alumina cup liner chipping. Fracture of a ceramic component is actually an episodic complication (0,08% in our experience), often caused by an uncorrect surgical technique, and shall not limit the use of this material.

Normal development of the infantile hip joint relies upon the congruent and stable relationship of the femoral head and the acetabulum. Treatment with dynamic bracing for instability of the hip joint is accepted, but the duration of treatment required and the timing of follow up is of current debate. The aim of this study was to determine the outcome of Pavlik Harness treatment in children with early presenting ultrasonographically unstable and dislocated hips, independently of morphological appearance of the joint. Children suspected of having or to be high risk for DDH were assessed by clinical and ultrasound examination. Ultrasonographically unstable and dislocated hips were treated in the Pavlik harness and reviewed weekly with ultrasound. Once reduction had been maintained for six consecutive weeks weaning from the harness over the following 5 weeks was started. Thirty three children (37 hips) were treated. The mean follow up time was 2.9 years (6 weeks - 5.3 years). Six hips failed to remain reduced. There was no statistically difference in age at commencement of Pavlik harness treatment between the successful and unsuccessfully treated groups (p>0.1). Evaluation of the duration of splintage required to achieve reduction of the hip compared against the age of the child at the commencement of splintage revealed no statistically significant correlation (p>0.1) to be present. Early treatment of hip instability within the first weeks of life, even with an apparent normal morphology of the acetabular socket, results in normal joint development, decreasing the need for prolonged compliance with treatment. It may also reduce the incidence of late presentation, without increasing the rate of complications (0 in our series).