Background

Alignment and soft tissue (ligament) balance are two variables that are under the control of a surgeon during replacement arthroplasty of the knee. Mobile bearing medial unicompartmental knee replacements have traditionally advocated sizing the prosthesis based on soft tissue balance while accepting the natural alignment of the knee, while fixed bearing prosthesis have tended to correct alignment to a pre planned value, while meticulously avoiding overcorrection. The dynamic loading parameters like peak adduction moment (PKAM) and angular adduction Impulse (Add Imp) have been studied extensively as proxies for medial compartment loading. In this investigation we tried to answer the question whether correcting static alignment, which is the only alignment variable under the control of the surgeon actually translates into improvement in dynamic loading during gait. We investigated the effect of correction of static alignment parameter Hip Knee Ankle (HKA) angle and dynamic alignment parameter in coronal plane, Mean Adduction angle (MAA) on 1st Peak Knee Adduction Moment (PKAM) and Angular Adduction Impulse (Add Imp) following medial unicompartmental knee replacements.

Introduction and Aims: This is a prospective randomised trial comparing the ABG uncemented total hip replacement with the Charnley in 243 patients less than 65 years of age. A standardised protocol and anterolateral approach was used.

Method: The ABG I cup was used in combination with a polyethylene liner. All stems were templated and a 28mm cobalt chrome head was used. Early mobilisation with partial weightbearing for six weeks was allowed. In the Charnley group, Elite polyethylene cups were used in conjunction with 22mm monoblock stems. All hips were inserted with pressurised CMW cement. Patients were followed up annually. Standardised radiographs were taken at each visit and the Harris hip score and Merle d’Aubigné outcome measures recorded.

There were 222 hips available for follow-up, 96 ABG hips and 126 Charnley hips (17 died and 10 were lost to follow-up), with the mean age at surgery and mean length of follow-up comparable. Most hips were replaced due to osteoarthritis.

There was no significant difference in the mean Harris hip or Merle d’Aubigné scores at one year and at latest follow-up.

Results: Radiographic results demonstrated accelerated polyethylene wear in the ABG hips with mean polyethylene wear at seven years being 2.1mm compared with 0.9mm for Charnley hips. Wear associated lysis around the ABG cup was the major reason for failure, with a total of eight cups (8.3%) undergoing revision.

Conclusion: There was no evidence of subsidence of the stem or osteolysis around the stem despite the polyethylene wear. Conversely, in the Charnley group the stem was the major reason for failure with 12 stems (9.5%) being revised for aseptic loosening. The Kaplan Meier Survivorship at 10 years was 66.6% ± 19.1% for the ABG and ± 82% for the Charnley group. This was not significant.

38 patients were taken from the arthroscopic washout waiting list and randomised after informed consent to receive either a course of sodium hyaluronate injections or an arthroscopic washout. Those patients who had previously had an arthroscopic washout, an intraarticular injection in the last 6 months, mechanical symptoms or hypersensitivity to avian proteins were excluded. The injections were given using an aseptic technique after first aspirating the knee to dryness. An injection was given each week for 5 weeks. The washouts were performed using 0. 9% saline and debridement was undertaken as necessary. The outcome measures used were a visual analogue pain score (VAS), Knee Society function score (FS) and Lequesne index (LI).

19 people were randomised into each group. The groups were similar in terms of age, sex and analgesics used. 2 patients in the arthroscopy group declined arthroscopy after randomisation as their symptoms had improved. There was no significant difference in the pre-intervention VAS or LI. The FS was worse in the arthroscopy group (p< 0. 01). After treatment, 2 patients in each group moved from the area and were lost to follow up.

During the year, 5 patients from the sodium hyaluronate group underwent arthroscopy. 3 patients failed to improve and were listed for total knee replacement. The others had improved at 3 months.

At 1 year, the VAS (NS), FS (p< 0. 02) and LI (p< 0. 04) were all better in the sodium hyaluronate group.

Intra-articular sodium hyaluronate injections should be considered for use in selected patients with knee osteoarthritis without mechanical problems. Further study is required to confirm these findings and improve patient selection.