Aims

In recent years, the use of a collared cementless femoral prosthesis has risen in popularity. The design intention of collared components is to transfer some load to the resected femoral calcar and prevent implant subsidence within the cancellous bone of the metaphysis. Conversely, the load transfer for a cemented femoral prosthesis depends on the cement-component and cement-bone interface interaction. The aim of our study was to compare the three most commonly used collared cementless components and the three most commonly used tapered polished cemented components in patients aged ≥ 75 years who have undergone a primary total hip arthroplasty (THA) for osteoarthritis (OA).

Aims

Modern total knee arthroplasty (TKA) prostheses are designed to restore near normal kinematics including high flexion. Kneeling is a high flexion, kinematically demanding activity after TKA. The debate about design choice has not yet been informed by six-degrees-of-freedom in vivo kinematics. This prospective randomized clinical trial compared kneeling kinematics in three TKA designs.

Aims

Total wrist arthrodesis (TWA) produces a spectrum of outcomes. We investigated this by reviewing 77 consecutive TWA performed for inflammatory and post-traumatic arthropathies, wrist instability and as a salvage procedure.

Squeaking arising from a ceramic-on-ceramic (CoC) total hip replacement (THR) may cause patient concern and in some cases causes patients to seek revision surgery. We performed a meta-analysis to determine the incidence of squeaking and the incidence of revision surgery for squeaking. A total of 43 studies including 16 828 CoC THR that reported squeaking, or revision for squeaking, were entered into the analysis. The incidence of squeaking was 4.2% and the incidence of revision for squeaking was 0.2%. The incidence of squeaking in patients receiving the Accolade femoral stem was 8.3%, and the incidence of revision for squeaking in these patients was 1.3%.

Cite this article: Bone Joint J 2014;96-B:181–7.

Bicruciate-stabilised total knee replacement (TKR) aims to restore normal kinematics by replicating the function of both cruciate ligaments. We performed a prospective, randomised controlled trial in which bicruciate- and posterior-stabilised TKRs were implanted in 13 and 15 osteo-arthritic knees, respectively. The mean age of the bicruciate-stabilised group was 63.9 years (sd 10.00) and that of the posterior-stabilised group 63.2 years (sd 6.7). A control group comprised 14 normal subjects with a mean age of 67.9 years (sd 7.9). The patellar tendon angle (PTA) was measured one week pre-operatively and at seven weeks post-operatively during knee extension, flexion and step-up exercises.

At near full extension during step-up, the bicruciate-stabilised TKR produced a higher mean PTA than the posterior-stabilised TKR, indicating that the bicruciate design at least partially restored the kinematic role of the anterior cruciate ligament. The bicruciate-stabilised TKR largely restored the pre-operative kinematics, whereas the posterior-stabilised TKR resulted in a consistently lower PTA at all activities. The PTA in the pre-operative knees was higher than in the control group during the step-up and at near full knee extension. Overall, both groups generated a more normal PTA than that seen in previous studies in high knee flexion. This suggested that both designs of TKR were more effective at replicating the kinematic role of the posterior cruciate ligament than those used in previous studies.

Intramedullary reaming causes elevation in intramedullary pressure (IP) and extravasation of intramedullary contents into the venous blood system. This study was to evaluate the effect of an intramedullary suction system (ISS), recently developed in our laboratory, on the IP and fat extravasation in a sheep model.

Twelve skeletal mature sheep were assigned randomly to 2 experimental groups of 6 sheep: instrumentation and reamed intramedullary nailing without the ISS application and instrumentation and reamed intramedullary nailing with ISS application. During reaming, the IP was recorded at each step of the procedure. Haemo-dynamic parameters were monitored at pre-reaming, 10 min post-reaming, and 50 min post-reaming, including, mean arterial blood pressure (MABP), pulmonary artery pressure (PAP), pulmonary arterial CO2 (Paco2), heart rate (HR), and saturated oxygen (SaO2). Blood and lung tissue samples were collected for the examination of medullary fat intravasations.

Dramatic increases in IP were observed in non-ISS group at the six defined measuring times: before drilling, guide wire, reaming 8 mm (reamer size), 9 mm, reaming 10 mm, and reaming 11 mm. The IP during reaming was significantly lower in ISS group (guide wire, 15 mmHg; 8 mm, 13 mmHg; 9 mm, -1 mmHg; 10 mm, 3 mmHg; 11 mm, 16 mmHg) than in non-ISS group (guide wire, 28, 8 mm, 185 mmHg; 9 mm, 168 mmHg; 10 mm, 146 mmHg; 11 mm, 150 mmHg). These reductions were significant with the P values < 0.05 or 0.01. Paco2, was lower in ISS group than non-ISS group (32 and 40 mmHg, respectively), while SaO2 was higher in ISS group than non-ISS group (99 and 91 mmHg, respectively). Histological data revealed fat emboli in sheep lung tissue in non-ISS group. Total lipids in lung specimen was lower in ISS group (7.6 mg/g tissue) than in non-ISS group (13.6 mg/g, P=0.04).

We demonstrate the ISS in controlling the increase in IP occurring in long bone reaming. The ISS allows real time pressure recording and feedback to the operator. With this feedback, the operating surgeon is able to control the rate of forward reaming to prevent major increases in IP

This prospective study used magnetic resonance imaging to record sagittal plane tibiofemoral kinematics before and after anterior cruciate ligament reconstruction using autologous hamstring graft. Twenty patients with anterior cruciate ligament injuries, performed a closed-chain leg-press while relaxed and against a 150 N load. The tibiofemoral contact patterns between 0° to 90° of knee flexion were recorded by magnetic resonance scans. All measurements were performed pre-operatively and repeated at 12 weeks and two years.

Following reconstruction there was a mean passive anterior laxity of 2.1 mm (sd 2.3), as measured using a KT 1000 arthrometer, and the mean Cincinnati score was 90 (sd 11) of 100. Pre-operatively, the medial and lateral contact patterns of the injured knees were located posteriorly on the tibial plateau compared with the healthy contralateral knees (p = 0.014), but were no longer different at 12 weeks (p = 0.117) or two years postoperatively (p = 0.909). However, both reconstructed and healthy contralateral knees showed altered kinematics over time. At two years, the contact pattern showed less posterior translation of the lateral femoral condyle during flexion (p < 0.01).

We have studied the influence of weight-bearing on the measurement of wear of the polyethylene acetabular component in total hip arthroplasty using two techniques. The measured vertical wear was significantly greater when radiographs were taken weight-bearing rather than with the patient supine (p = 0.001, method 1; p = 0.007, method 2). Calculations of rates of linear wear of the acetabular component were significantly underestimated (p < 0.05) when radiographs were taken supine. There are two reasons for this. First, a change in pelvic orientation when bearing weight ensures that the thinnest polyethylene is brought into relief, and secondly, the head of the femoral component assumes the position of maximal displacement along its wear path. Interpretation of previous studies on both linear and volumetric polyethylene wear in total hip arthroplasty should be reassessed in the light of these findings.