There is little published literature to support the claim that a successful total knee replacement (TKR) is predictive of future good outcomes on the contralateral side. The objective was to identify whether outcome from the first of staged TKRs could be used to predict the outcome of the contralateral TKR.

This was a retrospective cohort study of 1687 patients over a 25-year period undergoing staged bilateral TKRs in a UK arthroplasty centre. A control group of 1687 patients undergoing unilateral TKR with matched characteristics was identified. Primary outcomes were satisfaction and Knee Society Score (KSS) at one year.

Preoperative status was comparable for pain, ROM and KSS (mean 41, 45, 43±14). At one year follow up, dissatisfaction was similar for all groups (4% first of staged TKR, 4% second of staged TKR, 5% controls). If the first TKR had a good outcome, the relative risk of a contralateral bad outcome was 20% less than controls (95% CI 0.6–1.2). If the first TKR had a poor outcome, the risk of a second poor outcome was 4 times higher (95% CI 2.8–6.1), increasing from 6% to 27% (absolute risk).

Patients undergoing the second of staged TKRs with a previous good outcome are likely to do well in their second procedure (94 in 100 will go on to have a second good outcome). Of those with a previous poor outcome, 27 in 100 will have a second poor outcome. The trend was persistent despite correcting for gender, age, BMI, and diagnosis.

Abstract

Abstract

It is anecdotally thought that a good outcome from the first of staged total hip arthroplasties (THAs) is predictive of benefit on the contralateral side. The objective was to determine whether outcome from the first THA could be used to predict outcome from the second, contralateral THA.

A retrospective cohort study of consecutive patients undergoing staged THAs at a UK arthroplasty centre over 25-years (1995–2020). A control THA group was identified and matched for age, gender, BMI, implant and diagnosis. One-year patient-reported outcome data was available for 91% 1543/1700.

1700 patients who underwent staged THA were compared to 1700 matched controls. Preoperative status was comparable for pain, function, and modified Harris hip score (mHHS, mean 41 SD 13 for both groups).

At one year, there was a 2% dissatisfaction rate in all groups (first of staged THAs, second of staged THAs and controls). Groups were similar in terms of pain, function and mHHS (mean 88 SD 11 for all groups). For every 100 patients undergoing staged THAs, 87 had a bilateral good outcome (mHHS >70 both), 11 had unilateral poor outcome (mHHS >70 one, <70 other) and 2 had bilateral poor outcome (mHHS <70 both).

If the first THA had a good outcome, the relative risk of a bad outcome was 20% less than for controls (RR 0.8 95% CI 0.6–1.1). If the first THA had a poor outcome, the risk of a second poor outcome was 4.5 times higher (RR 4.5 95% CI 3.2–6.4), increasing from 6% to 29% (absolute risk).

Patients undergoing staged THAs with a good outcome from the first THA were less likely to have a bad outcome with the second. Risk of a poor outcome after a previous successful THA was 6% but rose to almost 30% with a previous poor outcome. This remained after correcting for patient variables including gender, age, BMI and diagnosis, indicating a potentially novel independent risk factor for poor outcome from staged THA.

The Pronator Quadratus (PQ) is commonly damaged in the surgical approach to the distal radius during volar plating. This study explored the functional strength of the PQ muscle, 12 months after volar plating of a distal radial fracture.

Testing of treated and contralateral forearms was carried out using a custom-made Torque Measuring Device (TMD) and surface Electromyography (sEMG). To assess both the direct and indirect function of PQ in participants treated with volar plating and compared to the contralateral non-injured forearms. The angle of elbow flexion was varied from 45o, 90o and 135o when measuring forearm pronation. Mean peak torque of the major pronating muscles, PQ and Pronator Teres (PT) was directly measured with the TMD and the indirect activation of the PQ and PT was measured with sEMG.

In total 27 participants were studied. A statistically significant reduction in mean peak pronation torque was observed in the volar plated forearms (P<0.05 SE 0.015, CI 95%). This is unlikely to be of clinical significance as the mean reduction was small (13.43Nm treated v 13.48Nm none treated). Pairwise comparison found no statistically significant reduction in peak torque between 45o, 90o and 135o of elbow flexion. There was an increase in PQ muscle activation at 135o compared to 45o elbow flexion. The converse was identified in PT.

The small but statistically significant difference in mean peak torque in treated and uninjured forearms is unlikely to be of clinical significance and results suggest adequate functional recovery of the PQ after volar plating.

Laminar airflow systems are universal in current orthopaedic operating theatres and are assumed to be associated with a lower risk of contamination of the surgical wound and subsequent early infection. Evidence to support their use is limited and sometimes conflicting. We investigated whether there were any differences in infection rates (deep and superficial) between knee and hip arthroplasty cases performed in non-laminar and laminar flow theatres at 10 year follow-up.

Between 2002 and 2006, 318 patients underwent knee and hip arthroplasty in a non-laminar flow theatre. Prospectively collected local arthroplasty audit data was collected including superficial and deep infection, revision for infection and functional outcomes. A cohort of patients from the same time period, who underwent knee and hip arthroplasty in a laminar flow theatre, were matched for age, sex, body mass index (BMI), operative approach, implant and experience of surgeon.

Superficial infection rates were lower overall in the non-laminar flow theatre (2.2percnt; versus 4.7percnt;), with a significantly lower superficial infection rate for knee arthroplasty performed in the non-laminar flow theatre (2percnt; versus 6.9percnt;). The deep infection rates were similar (1.3percnt; vs 1.9percnt;) for both laminar and non-laminar flow theatre respectively. Revision rates for infection were similar between both groups (0.9percnt; in non-laminar flow theatre vs 0.3percnt; in laminar flow)

Whilst the causes of post-operative surgical site infection are multifactorial, our results demonstrate that at long –term follow-up, there was no increased risk of infection without laminar flow use in our theatre.

Total Hip Arthroplasty (THA) is one of the most successful and cost-effective treatments available for painful hip arthritis. Unfortunately, dislocation following primary THA is one of the most common complications, occurring in approximately 0.50–10percnt; cases. However, there is little literature that investigates the effects that dislocation has on the patient's overall function and satisfaction.

We reviewed 229 THA patients that had sustained dislocation from a prospective database, consisting 156 single dislocations and 73 with two or more. Patient outcomes were compared with a matched control group of 196 patients without dislocation in the same follow-up period. Harris Hip Score (HHS) and patient satisfaction were recorded pre-operatively and at one, five and ten years post-operatively. Mann-Whitney test compared HHS between control and dislocation groups, Chi-Square test compared patient satisfaction and implant survival.

Total HHS and functional component were significantly lower in the dislocation group at one, five and ten years (p<0.05). HHS Pain component revealed a significant difference but only at one and three years (p<0.05). Patient satisfaction only showed a significant difference at one-year review. Dislocation rates were significantly higher in females. Implant survivorship was significantly lower in the dislocation group at 15-years.

Hip-function and implant survival is significantly reduced following prosthesis dislocation, however patient satisfaction and pain levels appear unaffected at long-term follow-up.