Bruyère Reports

Shoe lifts for leg length discrepancy in adults with musculoskeletal conditions. A Bruyère Rapid Review.

Executive Summary

The objective of this rapid review is to evaluate the evidence of shoe lifts on pain, function, range of motion, patient satisfaction and quality of life in adults with leg length discrepancy associated with musculoskeletal conditions such as osteoarthritis, back pain and scoliosis.

Leg length discrepancy (LLD), is a condition in which paired lower limbs are noticeably unequal. It is associated with a range of musculoskeletal conditions such as low back pain, scoliosis, osteoarthritis (OA) of the hip or knee, and hip or knee flexion contractions. LLD causes pain and poor functional outcomes and it is a complication of total hip or knee replacement surgery (arthroplasty) for OA resulting in poor patient satisfaction.

The use of shoe lifts for correcting LLD in patients with low back pain, hip or knee OA reduces pain and improves functional outcomes. However, few studies have assessed the association of LLD and knee OA. The findings of this review will support the Bruyère rehabilitation team’s interest to explore the feasibility of de- signing a randomized controlled trial to assess the effects of using a shoe lift in the functionally shorter limb in patients with OA who have undergone total knee arthroplasty.

Given the limited availability of systematic reviews, we included a broader range of primary study designs including randomized trials, before-after studies, non- comparative cohort, case series, and case reports. Nine studies met the eligibility criteria.

We found very low quality evidence that using shoe lifts for LLD reduced pain, and improved function and range of motion. The included studies were in patients with LLD associated with back pain, hip pain or knee pain. No studies evaluated patients following total knee replacement surgery.

We also found three guidelines that recommended the use of shoe lifts, shoe modifications, or surgery for the treatment of limb length discrepancy in people with low back pain, hip and groin disorders and osteoarthritis. The recommendations were consensus-based reiterating the paucity of evidence in this area.

We therefore suggest that:

Studies should be done to evaluate the effect of shoe lifts in patients with LLD due to knee flexion con- tracture following total knee arthroplasty. Better quality, controlled studies should be done to confirm the effectiveness of shoe lifts on pain and functional out- comes in patients with hip and back pain.
Knee flexion contracture is a common orthopedic problem in the geriatric population and clinical prac- tice guidelines should be developed to address it.

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Background

The issue
Leg length discrepancy (LLD), is a condition in which paired lower limbs are noticeably unequal. It is associated with a range of musculoskeletal conditions such as low back pain, scoliosis, osteoarthritis (OA) of the hip or knee, and hip or knee flexion contractures. Musculoskeletal conditions are the most common cause of pain and disability, and second most common reason for healthcare utilization. The burden of these conditions, especially chronic joint pain and low back pain increases with aging. LLD also causes pain and poor functional outcomes and is a complication of total hip or knee replacement surgery (arthroplasty) for OA resulting in poor patient satisfaction.

Shoe lifts are used for LLD correction in patients with low back pain, hip or knee OA to reduce pain and improve functional outcome. However, few studies have assessed the association of LLD and knee OA.

Context
Bruyère Health (BCC) is the sole provider of complex continuing care in the Ottawa region and also provides rehabilitation care to diverse adult patients including the elderly. Approximately 10 to 20 percent of patients evaluated for painful musculoskeletal conditions are found to have an LLD and approximately one in ten patients have a knee flexion contracture following total knee joint arthroplasty. This amounts to a large number considering that well over 500 knee replacements are performed in Ottawa annually. Restricted joint mobility and pain associated muscle tightness result in joint contracture, leading to LLD post-total knee arthroplasty. Using shoe lifts in the shorter leg after knee arthroplasty would correct LLD, reduce pain and improve functional outcomes but there is little to no evidence-based guidelines describing post-arthroplasty treatment with shoe lifts.

In a 2015 study of patients with end-stage OA who had total knee arthroplasty, the BCC rehabilitation team found that knee flexion contracture in the surgical knee was associated with post-operative knee flex- ion contracture in the non-surgical knee. Knee flexion contracture prevents the full extension of the surgical knee joint causing loss of range of motion and functional LLD.

Compensating for the unequal leg length during walking resulted in knee flexion contracture in the non-surgical leg. The BCC rehabilitation team is interested to explore the feasibility of designing a randomized controlled trial to assess the effects of using a shoe lift in the shorter leg in patients with OA who have undergone total knee arthroplasty. This rapid review is undertaken to support the Bruyère feasibility study by providing a review of findings from existing studies.

Objectives

Methods

We planned to include clinical practice guidelines and systematic reviews. Due to the paucity of evidence, we decided to include a broader range of primary study designs including randomized trials, controlled before-after studies, cohort, case series, and case reports that met the eligibility criteria.

Literature Search

We searched the Cochrane Library (CENTRAL), PubMed, PEDro and Trip database using the following search terms: shoe lifts, shoe, leg length inequality, leg length discrepancy, limb length inequality and limb length discrepancy. We identified 303 articles.

We screened reference lists of potential articles and did a related article search in PubMed. We also searched the National Guideline Clearinghouse database.

Relevance assessment
We screened the search results in duplicate and disa- greements were resolved by consensus. We identified 9 primary studies: one randomized controlled trial (RCT); two before-and-after studies; one non-comparative cohort study; three case series and two case reports that met our eligibility criteria.

We reviewed a sample of nine guidelines relevant to leg length discrepancy and musculoskeletal conditions from high-income country settings. We selected the sample based on recency and high-income coun- try setting. We reviewed: the American College of Rheumatology (ACR) osteoarthritis guidelines; Osteoarthritis Research Society International (OARSI) guidelines; European League Against Rheumatism (EULAR) osteoarthritis guidelines; the National Institute for Health and Care Excellence (NICE) osteoarthritis guidelines; the Toward Optimized Practice (TOP) Program guideline for the Evidence-Informed Primary Care Management of Low Back Pain; the American Occupational Medicine Practice Guidelines for Hip and groin disorders[18]; the American Occupational Medicine Practice Guidelines for low back disorders [19] and the Prescription Custom Foot Orthoses Practice (PCFO) Guidelines of the American College of Foot and Ankle Orthopedics and Medicine. We identified three guidelines from the sample that recommended the use of shoe lifts, shoe modifications or surgery for leg length discrepancy in low back disorders, hip and groin disorders and osteoarthritis.

Critical appraisal
We assessed the quality of the included primary studies using the Cochrane risk of bias tool for the RCT and the NIH quality assessment tool for before and after studies, non-comparative cohort studies, case-series and case report studies.

We assessed the quality of the relevant guidelines with AGREE II.

We also assessed the quality of the evidence with GRADE.

Evidence Review

We identified 9 studies that met the inclusion criteria: one randomized controlled trial (RCT), two before after studies, one non-comparative cohort, three case series and two case reports.

We also identified three clinical practice guidelines that recommended the use of shoe lifts or shoe modification for leg length discrepancy in low back disorders, hip and groin disorders, and osteoarthritis. These recommendations were based on consensus. Synthesis of findings from primary studies.

LLD was associated with various musculoskeletal conditions. Some patients had low back pain with or without scoliosis; others had hip or knee pain. One study was in patients after hip arthroplasty. One study re- ported the case of a patient with LLD after damage to the distal epiphyseal plate of her right tibia. LLD was measured in all patients but the magnitude was not reported in one study with patients who had hip arthroplasty. The magnitude ranged from 0-45 mm in the study populations. In one of the included studies, shoe lift therapy was administered in combination with manipulation therapy.

One small RCT with high risk of bias (no description of randomization and allocation concealment as well as no blinding) and seven observational studies (including one before-after study one cohort, three case series and two case reports with no control groups) assessed outcomes of interests.

We also identified three clinical practice guidelines that recommended the use of shoe lifts or shoe modification for leg length discrepancy in low back disorders, hip and groin disorders, and osteoarthritis. These recommendations were based on consensus.

Synthesis of findings from primary studies

LLD was associated with various musculoskeletal con- ditions. Some patients had low back pain with or without scoliosis; others had hip or knee pain. One study was in patients after hip arthroplasty. One study reported the case of a patient with LLD after damage to the distal epiphyseal plate of her right tibia. LLD was measured in all patients but the magnitude was not reported in one study with patients who had hip arthroplasty. The magnitude ranged from 0-45 mm in the study populations. In one of the included studies, shoe lift therapy was administered in combination with manipulation therapy.

One small RCT with high risk of bias (no description of randomization and allocation concealment as well as no blinding) and seven observational studies (including one before-after study one cohort, three case series and two case reports with no control groups) assessed outcomes of interests.

Effect of shoe lifts on pain
One RCT showed benefit in patients with LLD and low back pain (Mean difference (MD) of 3.10, 95% CI 2.62 to 3.58; P<0.001; very low uncertainty).

Eight observational studies with no control also showed benefit in patients with LLD and low back pain, hip pain or knee pain. The effect size ranged from 66.7% to 100%.

However, we are uncertain whether shoe lifts reduce pain as the quality of the evidence is very low because of very serious study limitations.

Effect of shoe lifts on function or disability
One RCT showed improvement in function in people with LLD and low back pain (MD 1.4, 95% CI 0.31 to 2.49; P<0.05; very low certainty).

The use of shoe lifts was found to improve function in 75% of patients with LLD and back pain in one observational studies but the overall quality of the evidence was very low (see Table 4).

Effect of shoe lifts on range of motion
One observational study in patients with LLD and low back pain and scoliosis showed that shoe lifts im- proved range of motion; very low quality of evidence (see Table 4).

Effect of shoe lifts on patient satisfaction

Patient satisfaction was not assessed in any of the studies.

Effect of shoe lifts on quality of life

No study measured this outcome.

Clinical guidelines and practice recommendations

Two of the nine guidelines reviewed recommended the use of shoe lifts, or surgery for the treatment of limb length discrepancy and one guideline recommended the use of shoe modifications and surgery. The recommendations were consensus-based confirming the paucity of evidence in this area. One guideline recommended the use of shoe lifts in people with low back pain and leg length discrepancy of > 2 cm. The other two guidelines did not specify the magnitude of LLD in people with hip and groin disorders and osteoarthritis. One guideline commented that shoe lifts have few adverse effects, but no supporting data was cited. The three guidelines were of moderate to high quality.

Discussion

Applicability of evidence/implementation

We sought to evaluate the evidence of shoe lifts on pain, function, range of motion, patient satisfaction and quality of life in adults with leg length discrepancy and musculoskeletal conditions such as osteoarthritis, back pain and scoliosis. We found studies in patients with LLD and osteoarthritis of the hip, knee pain, back pain and damage to the distal epiphyseal plate of right tibia.

Different outcomes were assessed in different patient populations. Pain was assessed in all except the patient with damage to the distal epiphyseal plate of right tibia. Function was assessed in patients with back pain, hip pain, knee pain, and in patients after total hip arthroplasty. Range of motion was only assessed in patients with back pain and scoliosis. The case report on the patient with LLD and damage to the distal epiphyseal plate of right tibia assessed one outcome – oxygen consumption. No study assessed quality of life and patient satisfaction.

Shoe lifts were effective on pain in patients with hip pain, knee pain and back pain. There was improved function and range of motion in patients with back pain. However, the quality of evidence is very low due to major study limitations. It is unclear if the effects of the treatment could be attributed to shoe lifts alone as some patients with back pain in one of the studies received combined treatment with shoe lifts and manipulation.

We found no evidence on the effectiveness of shoe lifts in patients with LLD after hip or knee arthroplasty.

Strengths and limitations

This rapid review was undertaken to support the BCC rehabilitation team to explore the feasibility of designing a randomized controlled trial to assess the effects of using a shoe lift in patients with OA who have had total knee arthroplasty. However, we found no studies in this patient population.

The shoe lift is a simple and inexpensive intervention that could be used for the correction of leg length discrepancy in patients after hip or knee arthroplasty and in patients with low back pain. We found low quality studies confirming the effectiveness of shoe lifts on pain and function outcomes in patients with hip and back pain but the study of shoe lifts in patients with knee pain only assessed pain relief. Six studies assessed shoe lifts in patients with back pain. Most (90%) of the studies were very small with less than 50 participants. It is unclear if the effects of the treatment could be attributed to shoe lifts alone as some patients in one of the studies received combined treatment with shoe lifts and manipulation.

There is disagreement about shoe lifts being the correct treatment for LLD of >20 mm magnitude. Other suggested treatment options are surgical correction of the LLD. We found shoe lifts to be effective on pain and function in all the included studies regardless of the magnitude of LLD (range from 0-45 mm). However, one study indicated no effect in one third of the included patients with low back pain but did not state if this was related to the magnitude of the LLD. One other study found partial pain relief in two patients with low back pain and their magnitude of LLD was 6 and 7 mm respectively.

Shoe lift is an inexpensive intervention and the diagnosis of LLD is sometimes overlooked leading to costly investigations such as myelograms and computed tomography (CT) scans in a search for an etiology for low back pain.

Implications

Based on our findings we conclude that:

Studies should be done to evaluate the effect of shoe lifts in patients with LLD due to knee flexion contracture following total knee arthroplasty. Better quality studies should be done to confirm the effectiveness of shoe lifts on pain and functional outcomes in patients with hip and back pain.
Knee flexion contracture is a common orthopedic problem in the geriatric population and clinical practice guidelines should be developed to address it.

Bruyère Health Research Institute