Aim: To assess the safety and efficacy of a mini-incision surgical (MIS) approach to knee arthroplasty (TKA) compared to a traditional standard approach.

Background: TKA through less invasive approaches have become increasingly popular in recent years. These range from smaller skin incisions to the ‘quadriceps-sparing’ procedures. Claims of improved recovery time and other clinical/economic advantages have been tempered by concerns about the safety of such procedures. This study was designed to evaluate any potential advantages of a specific approach (MIS) whilst studying peri-operative, radiological and outcome data to examine procedural safety.

Patients and Methods: 80 patients undergoing TKA were randomised to a standard or MIS (mini-midvastus) approach. The latter involved patella subluxation, rather than eversion. The operative, anaesthetic and post-operative treatments were standardised including rehabilitation protocols. Strict discharge criteria were established and independently verified and patients were discharged directly to their homes capable of independent care. Specifically the study evaluated patient demographics, operative time, blood loss and hospital stay. Outcome data including Knee Society Scores, Oxford Knee Scores and SF36 were recorded regularly in the early recovery period and up to 1 year post-operatively. Independent radiological review of implant positioning and alignment was obtained.

Results: There were no significant differences in operative time, blood loss, or other intra-operative data. Accelerated discharge was achieved in both groups (compared to historic data), however the length of stay (LOS) was significantly shorter in the MIS patients (mean – 3.5 days compared with 4.4 days in the standard patients). There was no statistical difference in clinical outcome analyses between the groups.

Discussion: Less invasive approaches to TKA have been reported over recent years but most studies have been anecdotal comparing patient recovery with historic controls which potentially can exaggerate clinical and economic benefits. Concerns have also been raised regarding the safety of these modified procedures. This study demonstrates a reduction in hospital stay and recovery in all patients as a result of accelerated rehabilitation. The MIS patients benefited from an additional significant reduction length of stay compared to controls with no evidence of compromise in terms of safety or efficacy.

Conclusions: This study has demonstrated the safety of the MIS mini-midvastus approach and a clear reduction in hospital length of stay. MIS surgery can offer substantial clinical and economic benefits but procedures must be closely evaluated to ensure equivalent or enhanced outcomes are achieved.

The National Institute for Clinical Excellence (NICE), in its “Guidance on the Selection of Prostheses for Primary Total Hip Replacement”, states that a revision rate of 10% or less at ten years should be regarded as the “benchmark” in the selection of prostheses for primary Total Hip Replacement (THR). This paper presents the results of such a study for primary Charnley THR. Methods: All patients undergoing primary Charnley THR during 1990 were prospectively registered with the Trent Regional Arthroplasty Study (TRAS). During 1990, 1198 Charnley THRs were performed on 1152 patients, under the care of 56 consultants, in 18 National Health Service and 6 private hospitals. The cohort contains 39.0% male and 61.0% female patients, with an average age at operation of 69.1years (21–103 years), 19.1% being less than 60 years. At 10 years all surviving patients at 5 years were registered with the ONS to ascertain living patients. These patients were contacted by letter to determine whether or not their THR had been revised. The status of the THR, for non-responding patients, was determined by contacting the patient’s GP through the Contractor Services Agency (CSA). The endpoint was defined as revision surgery to replace an original implant component. Results: At 10 years, the recipients of 438 THRs had died. The recipients of 89 THRs did not respond to the questionnaire at ten years. Implant status at ten years, in living patients was known for 671 of 760 (88.3%) THRs. The ten-year crude revision rate was 44 out of 1198 (3.7%) and cumulative survival rate was 95.5% (95% CI, 93.6% – 96.9%).

Conclusion: This is the first study to assess the survivorship at 10 years for primary Charnley THRs performed in the ‘general setting’ of the NHS as opposed to specialist centres and shows a result well within the NICE benchmark.

The Department of Health and the Public Health Laboratory Service established the Nosocomial Infection National Surveillance Scheme (NINSS) in response to the need to standardise the collection of information about infections acquired in hospital. This would provide national data that could be used as a ‘benchmark’ by hospitals to measure their own performance. The definition of superficial incisional infection (skin and subcutaneous tissue), set by Centers of Disease Control (CDC), should meet at least one of the following criteria: I: Purulent drainage from the superficial incision. II: The superficial incision yields organisms from the culture of aseptically aspirated fluid or tissue, or from a swab, and pus cells are present. III: At least two of the following symptoms and signs of inflammation: pain or tenderness, localized swelling, redness or heat, and a. the superficial incision is deliberately opened by a surgeon to manage the infection, unless the incision is culture-negative or b. clinician’s diagnosis of superficial incisional infection.

This study assessed the interobserver reliability of the superficial incisional infection criteria, set by the CDC, in current practice.

The incisional site of 50 consecutive patients, who underwent elective primary joint arthroplasty (Hips & Knees), were evaluated independently by four observers. The most significant results of the study I: All four observers achieved absolute agreement (kappa=1) for Purulent wound discharge and clinical diagnosis of wound infection. II: The four observers obtained good agreement for pain criteria (kappa=0.76, III: There was significant disagreement (fair to poor) between all four observers for the following criteria: Localized swelling (kappa=0.34), Redness (kappa=0.33) and tenderness (kappa = 0.05).

This is the first study to assess the reliability of the criteria, as set by the CDC and recommended by NINSS, for the diagnosis of superficial incisional infection and shows the Criterion III is not reliable and we recommend it should be revised. Failure to do so could lead to inaccurate statistics regarding hospital wound infection and detrimental effect on hospital trusts in the setting of league table.