Cross, Michael B.

Many aspects of total knee arthroplasty have changed since its inception. Modern prosthetic design, better fixation techniques, improved polyethylene wear characteristics and rehabilitation, have all contributed to a large change in revision rates. Arthroplasty patients now expect longevity of their prostheses and demand functional improvement to match. This has led to a re-examination of the long-held belief that mechanical alignment is instrumental to a successful outcome and a focus on restoring healthy joint kinematics. A combination of kinematic restoration and uncemented, adaptable fixation may hold the key to future advances.Cite this article: Bone Joint J 2015;97-B(10 Suppl A):16–19.

The aims of this study were to determine the functional impact and financial burden of isolated and recurrent dislocation after total hip arthroplasty (THA). Our secondary goal was to determine whether there was a difference between patients who were treated non-operatively and those who were treated operatively.We retrospectively reviewed 71 patients who had suffered dislocation of a primary THA. Their mean age was 67 years (41 to 92) and the mean follow-up was 3.8 years (2.1 to 8.2).Because patients with recurrent dislocation were three times more likely to undergo operative treatment (p < 0.0001), they ultimately had a significantly higher mean Harris Hip Score (HHS) (p = 0.0001), lower mean Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores (p = 0.001) and a higher mean SF-12 score (p < 0.0001) than patients with a single dislocation. Likewise, those who underwent operative treatment had a higher mean HHS (p < 0.0001), lower mean WOMAC score (p < 0.0001) and a higher mean SF-12 score (p < 0.0001) than those who were treated non-operatively.Recurrent dislocation and operative treatment increased costs by 300% (£11 456; p < 0.0001) and 40% (£5217; p < 0.0001), respectively.The operative treatment of recurrent dislocation results in significantly better function than non-operative management. Moreover, the increase in costs for operative treatment is modest compared with that of non-operative measures.Cite this article: Bone Joint J 2015; 97-B:1046–9.

Introduction Acetabular component position can be an important determinant of joint stability and bearing surface wear after THA. Nonetheless, the incidence of malpositioning is high. Patient obesity, low surgeon volume, and minimally invasive approaches are known risk factors for malposition. As the incidence of obesity continues to increase, it is important to recognise its effect on intraoperative component positioning in THA. Objectives Our goal was to assess the impact of obesity on component position for a high-volume surgeon using a standard postero-lateral approach. Methods A consecutive series of 120 obese (BMI >30, mean BMI 34.4) and 120 non-obese patients (mean BMI 25.4), who had undergone primary THA by a single surgeon, were included in our retrospective study. AP pelvis and cross-table radiographs obtained at the first postoperative visit were analysed using EBRA software to determine inclination and anteversion angles. Optimal position was defined as 30-45° of inclination and 5-25° of anteversion. Results Mean inclination and anteversion were 40.6 (+/-5.4°) and 16.6 (+/-5.5°) respectively, in the obese group and 39° (+/-5.0°) and 16.2° (+/-7.5°) in the non-obese group. In the obese group 89 (74%) patients were within the desired range for both measurements, 31 (26%) were out of range in at least one, compared to 91 (76%) and 29 (24%) in the non-obese group, respectively. The overall incidence of malpositioning was 25% for both groups. Among outliers, mean deviation from the optimal range was ≤3.8° in both groups. Conclusions The risk of component malpositioning in THA may be reduced when surgery is performed by an experienced, high volume surgeon utilising a standard posterolateral approach. In this setting the deleterious effect of obesity may be overcome.