Joint distraction for knee osteoarthritis without alignment correction

# Recommendations
Current evidence on the safety and efficacy of joint distraction for knee osteoarthritis without alignment correction is inadequate in quantity and quality. Therefore, this procedure should only be used in the context of research.
Further research into joint distraction for knee osteoarthritis without alignment correction should include comparative studies against existing forms of management. Studies should record patient selection, joint space measurements in the medium to long term, functional outcomes, quality of life and complications. They should also report the nature and timing of any further surgery on the knee. NICE may update the guidance on publication of further evidence.# Indications and current treatments
Osteoarthritis of the knee is the result of progressive deterioration of the articular cartilage and menisci of the joint. Articular cartilage deteriorates because of injury, or wear and tear. This leads to exposure of the bone surface. Symptoms include pain, stiffness, swelling and difficulty walking.
Treatment for knee osteoarthritis depends on the severity of the disease. Conservative treatments include analgesics and corticosteroid injections to relieve pain and inflammation, and physiotherapy and prescribed exercise to improve function and mobility. When symptoms are severe, surgery may be indicated. Options include upper tibial osteotomy, microfracture surgery, and unicompartmental or total knee replacement.# The procedure
Joint distraction for knee osteoarthritis without alignment correction aims to offload and modify the mechanical environment in osteoarthritic joints to allow cartilage regrowth. Intra-articular surgery (such as debridement) may be done before distraction to stimulate cartilage healing.
With the patient under spinal block or general anaesthesia, pins are drilled through the tibia and femur. A distraction frame is then fitted external to the leg, unloading the knee by gradually increasing the distance between the cartilaginous surfaces of the knee (usually up to 5 mm) over a few days or weeks. The distraction is normally maintained for about 23 months before the frame is removed. During this time, the patient is able to walk. The continuous flow of synovial fluid through the joint (enhanced by the distraction) is claimed to support chondrocyte nutrition and regeneration of cartilage. However, the exact mechanisms that may lead to cartilage regeneration during distraction are not known.# Efficacy
This section describes efficacy outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.
A case series of 20 patients with end-stage knee osteoarthritis treated by joint distraction reported significant improvements in Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores (normalised to a 100point scale for total and subscales; 100 being the best score) of 70% at 1year follow-up and of 74% at 2year follow-up (p<0.001 for both improvements from baseline). The individual components of the WOMAC score (pain, stiffness and function) all improved significantly compared against baseline (p<0.005 for all 3 subscales at each time point: 3, 6, 12, 18 and 24 months). A case series of 6 patients with knee osteoarthritis treated by joint distraction reported a significant increase in the mean Japan orthopaedic association score (range from 0 to 100, with higher scores indicating better function) from 56 (range 5560) before the procedure to 81 (range 7085) at the latest follow-up (mean 3year follow-up, p<0.001).
A non-randomised comparative study of 61 patients treated by joint distraction and debridement (n=19) or debridement alone (n=42) reported a statistically significant improvement in pain (measured on a 4point Likert scale, with a higher score indicating more severe pain) in the joint distraction group 35 years after the procedure (p<0.004). In the debridement-only group, there was no statistically significant improvement in pain scores 35 years after the procedure (p=0.163). The case series of 20 patients reported a significant decrease in pain scores (measured on a 10point visual analogue scale, with a higher score indicating more severe pain) of -58% at 1year follow-up and of -61% at 2year follow-up (both improvements from baseline were significant; p<0.001).
The non-randomised comparative study of 61 patients treated by joint distraction and debridement or debridement alone reported a significant increase in walking capacity in the joint distraction group from 1035 minutes before the procedure to 3251 minutes 35 years after the procedure (p<0.001). In the debridement-only group, the walking capacity range was 1223 minutes before the procedure and 2031 minutes 35 years after the procedure (p=0.142). The non-randomised comparative study of 61 patients treated by joint distraction and debridement or debridement alone also reported a significant improvement in stair climbing in both groups. In the joint distraction group, none of the patients (0/19) had no difficulty in ascending or descending stairs before the procedure and 74% (14/19) of patients had no difficulty in stair climbing 35 years after the procedure (p<0.002). In the debridement-only group, 33% (13/42) of patients had no difficulty in stair climbing before the procedure and 67% (28/42) of patients had no difficulty in stair climbing 35 years after the procedure (p<0.001).
The case series of 20 patients reported a significant change in mean cartilage thickness from baseline for the total subchondral bone area of the most affected compartment of 0.6 mm (95% confidence interval  0.24 mm to 1.22 mm) at 1year follow-up (p=0.002) and of 0.4 mm (95% CI 0.06 mm to 0.83 mm) at 2year follow-up (p=0.03) (no further details reported).
The non-randomised comparative study of 61 patients treated by joint distraction and debridement or debridement alone reported mean joint spaces on X-ray in the joint distraction group of 2.5 mm before the procedure and of 4.3 mm 35 years after the procedure (p<0.001); in the debridement-only group, mean joint spaces were 2.7 mm before the procedure and 2.4 mm 35 years after the procedure (p=0.135). The case series of 20 patients reported a significant change in the minimum joint space width in the most affected compartment from baseline of 59% (0.57 mm, 95% CI 0.09 mm to 1.06 mm; p=0.03) after 2 years. The change in mean joint space width in the most affected compartment from baseline was 21% (0.36 mm, 95% CI 0.13 mm to 0.85 mm; p=0.11) after 2 years.
The specialist advisers listed key efficacy outcomes as improvement in pain symptoms, improved function, increase in joint space and a delay in the need for joint replacement.# Safety
This section describes safety outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.
Deep vein thrombosis was reported in 11% (2/19) of patients treated by joint distraction in a non-randomised comparative study of 61 patients treated by joint distraction and debridement (n=19) or debridement alone (n=42); in 1 patient the thrombosis resolved after heparinisation and 1 patient developed a non-fatal pulmonary embolism (no further details provided). Pulmonary embolism was reported in 10% (2/20) of patients in a case series of 20 patients with end-stage knee osteoarthritis; both patients were treated by oral anticoagulants for 6 months (no further details provided).
Pin track infections were reported in 18% of patients (absolute number not given) treated by knee joint distraction in the nonrandomised comparative study of 61 patients treated by joint distraction and debridement (n=19) or debridement alone (n=42); all patients responded completely to local cleaning and systemic antibiotics (no further details provided). Pin track infections were reported in 85% (17/20) of patients treated by knee joint distraction in the case series of 20 patients; all the infections were treated by oral antibiotics (flucloxacillin; no further details provided). Superficial skin infections around the insertion of the pins were reported in 33% (2/6) of patients treated by knee joint distraction in a case series of 6 patients with knee osteoarthritis (no further details provided).
Limited flexion immediately after treatment was reported in all patients (20/20) in the case series of 20 patients (mean -31.6o of flexion, 95% confidence interval  -43.9o to -19.2o). Flexion improved at 6 months (mean -7.2o of flexion, 95% CI -15.2o to 1.1o) and flexion range fully normalised within 1 year (mean +2.9o of flexion, 95% CI -3.3o to 9.1o).
In addition to safety outcomes reported in the literature, specialist advisers are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never done so). For this procedure, specialist advisers did not list any anecdotal adverse events. They considered that the following were theoretical adverse events: stress fracture at pin site, creation of deformity, pain, risk of worsening symptoms and failure to give benefit.# Further information
For related NICE guidance, see the NICE website.

# Information for patients
NICE has produced information on this procedure for patients and carers (information for the public). It explains the nature of the procedure and the guidance issued by NICE, and has been written with patient consent in mind.# About this guidance
NICE interventional procedures guidance makes recommendations on the safety and efficacy of the procedure. It does not cover whether or not the NHS should fund a procedure. Funding decisions are taken by local NHS bodies after considering the clinical effectiveness of the procedure and whether it represents value for money for the NHS.
This guidance was developed using the NICE interventional procedures guidance process.
We have produced information for the public explaining this guidance. Information about the evidence the guidance is based on is also available.
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Your responsibility
    This guidance represents the views of NICE and was arrived at after careful consideration of the available evidence. Healthcare professionals are expected to take it fully into account when exercising their clinical judgement. This guidance does not, however, override the individual responsibility of healthcare professionals to make appropriate decisions in the circumstances of the individual patient, in consultation with the patient and/or guardian or carer.
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     National Institute for Health and Care Excellence 2015. All rights reserved. NICE copyright material can be downloaded for private research and study, and may be reproduced for educational and not-for-profit purposes. No reproduction by or for commercial organisations, or for commercial purposes, is allowed without the written permission of NICE.
ISBN: 978-1-4731-1303-9