Background

Chronic pain after joint replacement is common, affecting approximately 10% of patients after total hip replacement (THR) and 20% of patients after total knee replacement (TKR). Heightened generalised sensitivity to nociceptive input could be a risk factor for the development of this pain. The primary aim of this study was to investigate whether preoperative widespread pain sensitivity was associated with chronic pain after joint replacement.

Background

To investigate whether the interaction between pre-operative widespread hyperalgesia and radiographic osteoarthritis (OA) was associated with pain severity before and after total hip replacement (THR) and total knee replacement (TKR).

Background

While many studies have investigated long-term outcomes after lower limb arthroplasty, rather less is known about the trajectory of short-term outcomes in the first post-operative year. It is difficult for a surgeon to know when, in terms of disease severity, it is best to operate, or to make an accurate prediction of the patient pattern of post-operative recovery. We explored the trajectory of change in pain and function following primary hip and knee arthroplasty and the influence of pre-operative self-reported symptoms on post-operative improvements.

Objective

There is limited information about the extent to which the association between pre-operative and chronic post-operative pain is mediated via pain-on-movement or pain-at-rest. We explored these associations in patients undergoing total hip (THR) and total knee (TKR) replacement.

Background

Total hip replacement (THR) and total knee replacement (TKR) are usually effective at relieving pain; however, 7–23% of patients experience chronic post-surgical pain. These trials aimed to investigate the effect of local anaesthetic wound infiltration on pain severity at 12 months after primary THR or TKR for osteoarthritis.

Physical functioning in patients undergoing hip surgery is commonly assessed in three ways: patient-reported outcome measure (PROM), performance test, or clinician-administered measure. It is recommended that several types of measures are used concurrently to capture an extended picture of function. Patient fatigue and burden, time, resources and logistical constraints of clinic and research appointments mean that collecting multiple measures is seldom feasible, leading to focus on a limited number of measures, if not a single one. While there is evidence that performance-tests and PROMs do not fully correlate, correlations between PROMs, performance tests and clinician-administrated measures are yet to be evaluated. It is also not known if the associations between function and patient characteristics depend on how function is measured. The aim of our study was to use different measures to assess function in the same group of patients before their hip surgery to determine 1. how well PROMs, performance tests and clinician-administrated measures correlate with one another and 2. Whether these measures are associated with the same patient characteristics.

We conducted a cross-sectional analysis of the pre-operative information of 125 participants listed for hip replacement. The WOMAC function subscale, Harris Hip Score (HHS) and walk-, step- and balance-tests were assessed by questionnaire or during a clinic visit. Participant socio-demographics and medical characteristics were also collected. Correlations between functional measures were investigated with correlation coefficients (r). Regression models were used to test the association between the patient's characteristics and each of the three types of functional measures.

None of the correlations between the PROM, clinician-administrated measure and performance tests were very high (r<0.90). The highest correlations were found between the WOMAC-function and the HHS (r=0.7) or the Walk-test (r=0.6), and between the HHS and the walk-test(r=0.7). All the other performance-tests had low correlations with the other measures(r ranging between 0.3 and 0.5).

The associations between patient characteristics and functional scores varied by type of measure. Psychological status was associated with the WOMAC function (p-value<0.0001) but not with the other measures. Age was associated with the performance test measures (p-value ranging from ≤0.01 to <0.0001) but not with the WOMAC function. The clinician-administered (HHS) measure was not associated with age or psychological status.

When evaluating function prior to hip replacement clinicians and researchers should be aware that each assessment tool captures different aspects of function and that patient characteristics should be taken into account. Psychological status influences the perception of function; patients may be able to do more than they think they can do, and may need encouragement to overcome anxiety. A performance test like a walk-test would provide a more comprehensive assessment of function limitations than a step or balance test, although performance tests are influenced by age.

For the most precise description of functional status a combination of measures should be used. Clinicians should supplement their pre-surgery assessment of function with patient-reported measure to include the patient's perspective.

Around 20% of patients who have total knee replacement find that they experience long-term pain afterwards. There is a pressing need for better treatment and management for patients who have this kind of pain but there is little evidence about how to improve care. To address this gap we are developing a complex intervention comprising a clinic to assess potential causes of a patient's long-term pain after knee replacement and onwards referral to appropriate, existing services. The Medical Research Council recommends that development of complex interventions include several stages of development and refinement and involvement of stakeholders. This study comprises the penultimate stage in the comprehensive development of this intervention. Earlier stages included a survey of current practice, focus groups with healthcare professionals, a systematic review of the literature and expert deliberation.

Healthcare professionals from diverse clinical backgrounds with experience of caring for patients with long-term pain after knee replacement were sent a study information pack. Professionals who wished to participate were asked to return their signed consent form and completed study questionnaire to the research team. Participants rated the appropriateness of different aspects of the assessment process and care pathway from 1–9 (not appropriate to very appropriate). Data were collated and a document prepared, consisting of anonymised mean appropriateness ratings and summaries of free-text comments. This document was then discussed in 4 facilitated meetings with healthcare professional held at the future trial centres. A summary report and revised care pathway was then prepared and sent to participants for further comments.

28 professionals completed the questionnaire and/or attended a meeting. Participants included surgeons, physiotherapists, nurses, pain specialists and rheumatologists. Mean appropriateness scores ranged from 6.9 to 8.4. Taking a score of 7–9 as agreement, consensus was achieved that the assessment should be performed at 3 months post-operative by an extended scope practitioner/nurse, treatment be guided by a standardised assessment of pain, and treatment individualised. There was also agreement that referrals in the care pathway to surgical review, GP and pain clinics were appropriate. Nurse-led/self-monitoring was rated lower (6.9) because of considerations about the need to ensure that patients receive appropriate support, follow-up and referral to other services.

This work demonstrates the research methods that can be used to refine the design of a complex intervention. The process and findings enable refinement of an intervention for patients with long-term pain after knee replacement. The next stage of intervention development will assess the acceptability and reliability of the assessment process, and the usability of the intervention's standard operating procedures. The intervention will then be evaluated by a larger research team in a multi-centre randomised controlled trial, starting in late 2016.

Purpose

Great expense is accumulated in investigation and management, often with poor outcome, of a patient with a painful TKR. We aim to produce guidelines for their investigation and careful, successful management.

Introduction: Although the primary aim of Total Knee Replacement (TKR) is to relieve chronic joint pain, 10–20% of patients experience unexplained chronic pain after surgery. One possible cause of this pain is central sensitisation. Prolonged exposure to a noxious input can lead the central nervous system to become sensitised to pain (central sensitisation), which can become self-sustaining and persist after the removal of the noxious stimuli i.e after TKR. The aim of this study was to determine if knee osteoarthritis (OA) patients awaiting TKR have evidence of sensory perception abnormalities, by comparing detection and pain thresholds from OA patients to those of age- and gender-matched healthy participants.

Patients and Methods: Quantitative Sensory Testing (QST) was performed on 107 knee OA patients on the waiting list for primary TKR and 50 age- and gender-matched healthy participants without knee pain or TKR. QST assesses somatosensory function through measuring participant responses to external stimuli of controlled intensity. QST was performed on both knees and the pain-free forearm of all participants. Von Frey filaments were used to measure touch detection thresholds, a digital Algometer to measure pressure pain thresholds, and the MSA Thermotest to measure detection and pain thresholds to hot and cold. Significant differences in the median threshold values between knee OA patients and healthy participants were tested for using Mann-Whitney U tests.

Results: Detection thresholds: OA patients had significantly higher detection thresholds for hot and cold (both p< 0.05) in the index knee (but not at other sites) compared to healthy participants. Touch detection thresholds were significantly higher at all body sites in OA patients compared to healthy participants (all p< 0.001).

Pain thresholds: Pressure pain thresholds were significantly lower in OA patients at all body sites (all p< 0.001) but there were no significant differences in hot or cold pain thresholds between OA patients and healthy participants at any body site (all p> 0.05).

Discussion: This study showed that knee OA patients have modality-specific sensory and pain perception abnormalities. These included thermal hypoesthesia (reduced sensitivity) in the index knee and tactile hypoesthesia at all body sites tested, alongside hyperalgesia (increased pain sensitivity) to pressure pain at all body sites. Future research aims to determine if these sensory perception abnormalities are predictive of chronic pain after TKR.

Introduction: Joint replacement has a low mortality rate, few adverse occurrences, excellent survivorship and is considered a cost-effective intervention to reduce disability in the community. However, the assessment of complications and survivorship fail to measure the success of joint replacement in achieving pain relief and restoration of functional ability. The aim of this large cross-sectional postal survey was to provide information on the prevalence of pain, disability, poor quality of life and patient dissatisfaction at 1–3 years after a range of lower limb orthopaedic surgeries in the UK.

Patient and Methods: A questionnaire was posted to all 3,125 consecutive alive patients who underwent a primary THR, hip resurfacing, TKR, UKR or patellar resurfacing at the Avon Orthopaedic Centre between January 2004 – April 2006. The questionnaire included the WOMAC, HOOS/KOOS quality of life scale and a validated satisfaction scale. All questionnaires are scored on a 0–100 scale (worst-best) and a poor outcome was defined as a score of ≤ 50 on the outcome measure.

Results: Completed questionnaires were received from 2,085 patients (response rate of 67%). Patients had a mean age of 67 years and 42% were male. The mean length of follow-up was 28 months (range 14–44 months). 911 patients had a THR, 157 patients had a hip resurfacing, 866 patients had a TKR, 100 patients had a UKR and 51 patients had a patellar resurfacing.

Pain: the prevalence of poor outcomes were 6% of patients with a THR, 4% with a hip resurfacing, 12% with a TKR, 9% with a UKR and 31% with a patellar resurfacing.

Conclusion: This survey has provided descriptive data on the prevalence of patient-reported levels of pain, disability, poor joint-related quality of life and dissatisfaction after lower limb arthroplasty. It is important that patient-reported outcomes after joint replacement are rigorously assessed in order to provide information on which patients do poorly after surgery, with the aim of targeting these patients with an intervention to improve their outcome.

North Bristol Trust Small Grants Scheme provided funding for the consumables for this study.

The Bristol Knee Replacement Registry was established in the 1970’s and contains prospectively recorded data on 3024 patients. The present study examines the group of 812 patients for whom complete pre-operative and five year post-operative data is available in order to relate their eventual health status to the pre-operative demographic data and to disease severity. The group comprised 593 women and 219 men who had undergone either Kinematic, Total or Sled unicompartmental knee replacement.

Pre-operatively, the average American Knee Society Score (AKSS) was 89 with the elderly, rheumatoid patients and women having significantly lower scores.

Five years later the average AKSS had risen to 161 with patients of all ages, (including the over 80’s) gaining considerably. However, the rheumatoid patients remained more disabled as did women who had a final AKSS of 157 as opposed to 171 for the men (p< 0.01). In addition, a statistically significant finding was that those with the lowest pre-operative scores also had the lowest 5 year scores - they never catch up.

173 patients underwent bilateral knee replacement at separate times. Their pre-operative AKSS was significantly higher at the time of the second knee replacement (90) than the first (82) p< 0.01.

We conclude that since patients present earlier for their second TKR and those with most disability fail to catch up the procedure should be performed earlier in the natural history of the disease, especially in women.