Aims

For this retrospective cohort study, patients aged ≤ 30 years (very young) who underwent total hip arthroplasty (THA) were compared with patients aged ≥ 60 years (elderly) to evaluate the rate of revision arthroplasty, implant survival, the indications for revision, the complications, and the patient-reported outcomes.

Objectives

This study aimed to characterise and qualitatively grade the severity of the corrosion particles released into the hip joint following taper corrosion.

We present a series of 35 patients (19 men and 16 women) with a mean age of 64 years (36.7 to 75.9), who underwent total hip replacement using the ESKA dual-modular short stem with metal on-polyethylene bearing surfaces. This implant has a modular neck section in addition to the modular head. Of these patients, three presented with increasing post-operative pain due to pseudotumour formation that resulted from corrosion at the modular neck-stem junction. These patients underwent further surgery and aseptic lymphocytic vaculitis associated lesions were demonstrated on histological analysis.

Retrieval analysis of two modular necks showed corrosion at the neck-stem taper. Blood cobalt and chromium levels were measured at a mean of nine months (3 to 28) following surgery. These were compared with the levels in seven control patients (three men and four women) with a mean age of 53.4 years (32.1 to 64.1), who had an identical prosthesis and articulation but with a prosthesis that had no modularity at neck-stem junction. The mean blood levels of cobalt in the study group were raised at 50.75 nmol/l (5 to 145) compared with 5.6 nmol/l (2 to 13) in control patients.

Corrosion at neck-stem tapers has been identified as an important source of metal ion release and pseudotumour formation requiring revision surgery. Finite element modelling of the dual modular stem demonstrated high stresses at the modular stem-neck junction. Dual modular cobalt-chrome hip prostheses should be used with caution due to these concerns.

We report the outcome at ten to 15 years of two-stage revision for hip infection in 99 patients using the Prostalac articulated hip spacer system.

All the patients were contacted to determine their current functional and infection status using the Oxford-12, Short form-12, and Western Ontario and McMaster University Osteoarthritis Index questionnaires. A total of 11 of the 99 patients had a further infection, of whom seven responded to repeat surgery with no further sequelae. The mean interval between the stages was five months (1 to 36). We were able to review 48 living patients, with a mean age of 72 years (46 to 86), 34 (71%) of whom provided health-related quality-of-life outcome scores.

The mean follow-up was 12 years (10 to 15). The long-term success rate was 89% and with additional surgery this rose to 96%. The mean global Western Ontario and McMaster University Osteoarthritis Index score was 80.6 (sd 18.3). The mean Oxford-12 score was 74.0 (sd 22.3), and the mean Short form-12 score was 53.1 (sd 9.4) (mental) and 33.5 (sd 13.5) (physical). The mean satisfaction score was 90.5 (sd 15.3).

Two-stage revision for hip infection using a Prostalac interim spacer offers a predictable and lasting solution for patients with this difficult problem.

Degenerative problems of the hip in patients with childhood and adult onset neuromuscular disorders can be challenging to treat. Many orthopaedic surgeons are reluctant to recommend total hip replacement (THR) for patients with underlying neuromuscular disorders due to the perceived increased risks of dislocation, implant loosening, and lack of information about the functional outcomes and potential benefits of these procedures in these patients. Modular femoral components and alternative bearings which facilitate the use of large femoral heads, constrained acetabular components and perhaps more importantly, a better understanding about the complications and outcomes of THR in the patient with neuromuscular disorders, make this option viable. This paper will review the current literature and our experience with THR in the more frequently encountered neuromuscular disorders.

Cite this article: Bone Joint J 2014;96-B(11 Suppl A):27–31.

Aims

To investigate the longevity of uncemented fixation of a femoral component in total hip arthroplasty (THA) in patients with Dorr type C proximal femoral morphology.

This study compared component wear rates and pre-revision blood metal ions levels in two groups of failed metal-on-metal hip arthroplasties: hip resurfacing and modular total hip replacement (THR).

There was no significant difference in the median rate of linear wear between the groups for both acetabular (p = 0.4633) and femoral (p = 0.0872) components. There was also no significant difference in the median linear wear rates when failed hip resurfacing and modular THR hips of the same type (ASR and Birmingham hip resurfacing (BHR)) were compared.

Unlike other studies of well-functioning hips, there was no significant difference in pre-revision blood metal ion levels between hip resurfacing and modular THR.

Edge loading was common in both groups, but more common in the resurfacing group (67%) than in the modular group (57%). However, this was not significant (p = 0.3479). We attribute this difference to retention of the neck in resurfacing of the hip, leading to impingement-type edge loading. This was supported by visual evidence of impingement on the femur.

These findings show that failed metal-on-metal hip resurfacing and modular THRs have similar component wear rates and are both associated with raised pre-revision blood levels of metal ions.

We prospectively evaluated the long-term outcome of 158 consecutive patients who underwent revision total hip replacement using uncemented computer-assisted design-computer-assisted manufacture femoral components. There were 97 men and 61 women. Their mean age was 63.1 years (34.6 to 85.9). The mean follow-up was 10.8 years (10 to 12).

The mean Oxford, Harris and Western Ontario and McMaster hip scores improved from 41.1, 44.2 and 52.4 pre-operatively to 18.2, 89.3 and 12.3, respectively (p < 0.0001, for each). Six patients required further surgery. The overall survival of the femoral component was 97% (95% confidence interval 94.5 to 99.7). These results are comparable to those of previously published reports for revision total hip replacement using either cemented or uncemented components.

We report the use of porous metal acetabular revision shells in the treatment of contained bone loss. The outcomes of 53 patients with ≤ 50% acetabular bleeding host bone contact were compared with a control group of 49 patients with > 50% to 85% bleeding host bone contact. All patients were treated with the same type of trabecular metal acetabular revision shell. The mean age at revision was 62.4 years (42 to 80) and the mean follow-up of both groups was 72.4 months (60 to 102). Clinical, radiological and functional outcomes were assessed. There were four (7.5%) mechanical failures in the ≤ 50% host bone contact group and no failures in the > 50% host bone contact group (p = 0.068). Out of both groups combined there were four infections (3.9%) and five recurrent dislocations (4.9%) with a stable acetabular component construct that were revised to a constrained liner. Given the complexity of the reconstructive challenge, porous metal revision acetabular shells show acceptable failure rates at five to ten years’ follow-up in the setting of significant contained bone defects. This favourable outcome might be due to the improved initial stability achieved by a high coefficient of friction between the acetabular implant and the host bone, and the high porosity, which affords good bone ingrowth.

We performed 114 consecutive primary total hip arthroplasties with a cementless expansion acetabular component in 101 patients for advanced osteonecrosis of the femoral head. The mean age of the patients at surgery was 51 years (36 to 62) and the mean length of follow-up was 110 months (84 to 129).

The mean pre-operative Harris hip score of 47 points improved to 93 points at final follow-up. The polyethylene liner was exchanged in two hips during this period and one broken acetabular component was revised. The mean linear wear rate of polyethylene was 0.07 mm/year and peri-acetabular osteolysis was seen in two hips (1.9%). Kaplan-Meier analysis indicated that the survival of the acetabular component without revision was 97.8% (95% confidence interval 0.956 to 1.000) at ten years.

Our study has shown that the results of THA with a cementless expansion acetabular component and an alumina-polyethylene bearing surface are good.

Total hip replacement for high dislocation of the hip joint remains technically difficult in terms of preparation of the true acetabulum and restoration of leg length. We describe our experience of cementless total hip replacement combined with a subtrochanteric femoral shortening osteotomy in 20 hips with Crowe grade IV dislocation with a mean follow-up of 8.1 years (4 to 11.5). There was one man and 17 women with a mean age of 55 years (44 to 69) at the time of the operation.

After placment of the acetabular component at the site of the natural acetabulum, a cementless porous-coated cylindrical femoral component was implanted following a subtrochanteric femoral shortening osteotomy.

The mean Japanese Orthopedic Association hip score improved from a mean of 38 (22 to 62) to a mean of 83 points (55 to 98) at the final follow-up. The mean lengthening of the leg was 14.8 mm (−9 to 34) in patients with iliofemoral osteoarthritis and 35.3 mm (15 to 51) in patients with no arthritic changes. No nerve palsy was observed.

Total hip replacement combined with subtrochanteric shortening femoral osteotomy in this situation is beneficial in avoiding nerve injury and still permits valuable improvement in inequality of leg length.

Metal-on-metal bearings for total hip replacement (THR) are becoming increasingly popular. Improved wear characteristics mean that these articulations are being inserted into younger patients in the form of THR and resurfacing procedures. This has led to concerns regarding potential carcinogenicity because of the increased exposure to metal ions that the procedure brings.

We have studied the serum cobalt and chromium concentrations in patients who had primary, well-fixed Ring metal-on-metal THRs for more than 30 years. The levels of cobalt and chromium were elevated by five and three times, respectively compared with those in our reference groups. Metal-on-metal articulations appear to be the source of metal ions throughout the life of the prosthesis. In three patients who had undergone revision of a previous metal-on-metal THR to a metal-on-polyethylene replacement the levels of metal ions were within the normal range. The elevations of cobalt and chromium ions seen in our study were comparable with those in patients with modern metal-on-metal THRs.

Post-mortem retrieval of canine, cemented femoral components was analysed to assess the performance of these implants in the dog as a model for human total hip replacement (THR). Mechanical testing and radiological analysis were performed to determine the stability of the implant and the quality of the cement. Thirty-eight implants from 29 dogs were retrieved after time intervals ranging from 0.67 to 11.67 years. The incidence of aseptic loosening was 63.2%, much higher than in human patients (6% in post-mortem studies). Failure of the femoral implants began with debonding at the cement-metal interface, similar to that in implants in man. The incidence of aseptic loosening was much lower in bilateral than in unilateral implants. Significant differences were observed for three different designs of implant. While the dog remains the animal model of choice for THR, results from this study provide insight into interspecies differences in the performance of implants. For example, the performance of THR in dogs should be compared with that in young rather than in elderly human patients.

The best treatment for the active and lucid elderly patient with a displaced intracapsular fracture of the femoral neck is still controversial. Randomised controlled trials have shown that a primary total hip replacement is superior to internal fixation as regards the need for secondary surgery, hip function and health-related quality of life. Despite good results achieved with total hip replacement in this group, most orthopaedic surgeons still advocate hemiarthroplasty for this injury. We studied 120 patients with a mean age of 81 years (70 to 90) with an acute displaced intracapsular fracture of the femoral neck. They were randomly allocated to be treated with either a bipolar hemiarthroplasty or total hip replacement. Outcome measurements included peri-operative data, general and hip-specific complications, hip function and health-related quality of life. The patients were reviewed at four and 12 months.

The duration of surgery was longer in the total hip replacement group (102 minutes (70 to 151)) versus 78 minutes (43 to 131) (p < 0.001), and the intra-operative blood loss was increased 460 ml (100 to 1100) versus 320 ml (50 to 850) (p < 0.001), but there were no differences between the groups regarding any complications or mortality. There were no dislocations in either group. Hip function measured by the Harris hip score was significantly better in the total hip replacement group at both follow-up periods (p = 0.011 and p < 0.001, respectively). The health-related quality of life measure was in favour of the total hip replacement group but did not reach statistical significance (p = 0.818 at four months and p = 0.636 at 12 months).

These results indicate that a total hip replacement provides better function than a bipolar hemiarthroplasty as soon as one year post-operatively, without increasing the complication rate. We recommend total hip replacement as the primary treatment for this group of patients.