Purpose: The appropriate means of fixation for hemiarthroplasty of the hip is a matter of ongoing debate. Proponents of uncemented components cite the risk of perioperative mortality with cement implantation as justification for avoiding cement in certain patients. Because cement-related mortality is rare, we wished to compare the incidence of perioperative mortality in patients receiving cemented versus uncemented hemiarthroplasty using a large national database. Further, we wished to compare overall revision rate between fixation methods to assess their role in implant survivorship.

Method: All recorded hemiarthroplasty cases from the AOA National Joint Replacement Registry were cross-referenced to the Australian mortality data, and deaths at 1d, 7d, 28d, and one year were compared between groups. Further, subgroup analysis of monoblock, modular, and bipolar hemiarthroplasty were compared as a surrogate measure of different patient populations.

Results: Comparing all hemiarthroplasty procedures as a group, there was a a significantly increased mortality rate at day one post-operatively (p = 0.0005) when cement was used. By day 7, this trend reversed, revealing a reduced mortality risk with cement (p = 0.02). This trend reversal persisted at day 28 and one year post-operatively (p = 0.028 & p < 0.0001, respectively). With subgroup analysis, monoblock hemiarthroplasty revealed a similar trend reversal in early versus late mortality. Modular and bipolar hemiarthroplasty procedures failed to reveal a significant difference in mortality when cemented and uncemented components were compared at all time points. When fixation method was compared in different age groups, a favourable mortality rate was seen at one year when cemented monoblock components were used in patients aged 71–80, and in patients ≥81 years old (p = 0.005 & < 0.001, respectively). The opposite was true with cemented modular implants at one year in patients < 70 years old (p = 0.009). There was no significant difference in mortality between cemented and uncemented implants in any other age investigated. Revision rates were significantly higher in patients treated with uncemented hemiarthroplasty regardless of prosthesis type.

Conclusion: This study demonstrates a higher overall success rate, and comparable or reduced long-term mortality risk when cement is used in hip hemiarthroplasty.

Many designs of unicompartmental knee replacement show early and mid-term failure due to polyethylene wear. We studied the wear rate of congruent polyethylene meniscal bearings retrieved from failed Oxford unicompartmental knee replacements.

We examined 16 bearings, 0.8 to 12.8 years after implantation, measuring their thickness and comparing it with that of 14 unused bearings. The mean rate of penetration, which included the effects of wear at both upper and lower surfaces, was 0.036 mm per year (maximum 0.08). Bearings as thin as 3.5 mm wore no faster than thicker models, but ten with evidence of impingement had greater wear. The six bearings with no impingement showed a mean rate of penetration of 0.01 mm per year.

In unicompartmental knee replacement, careful implantation of fully congruous meniscal bearings can avoid failure due to polyethylene wear.

We investigated 42 patients who were being considered for primary total hip arthroplasty (THA), but in whom it was uncertain whether the hip was the source of their pain. They were given an injection of local anaesthetic into the joint space.

Of 33 patients who gained pain relief from their injection, 32 subsequently had successful THA. The remaining patient has not had surgery. The intra-articular injection of local anaesthetic is thus at least 96% sensitive. Of the nine patients who had no or only minimal pain relief from injection, one has had an unsuccessful THA, three have been successfully treated for other conditions and five have unresolved pain for which no organic basis has been established.

We believe that the injection of local anaesthetic into the hip is a reliable test, with low morbidity. In difficult cases it will aid in the clarification of the cause of pain which possibly arises from the hip.

We investigated 15 patients with painful hip arthroplasties using intra-articular injection of bupivicaine. Fourteen had pain relief and 13 of them were subsequently found to have loosening of one or both components. The relief of pain after total hip arthroplasty by intra-articular injection of bupivicaine indicates that a satisfactory result is probable after revision surgery with refixation of the components.