Department of Orthopaedic Surgery, Nepal Medical College Teaching Hospital, Kathmandu, Nepal
Received date: August 16, 2016; Accepted date: September 07, 2016; Published date: September 11, 2016
Citation: Shah RK, Shrivastava MP, Adhikari V. Clinico-Radiological Study of Polycentric Knee Brace in Osteoarthritis of Knee. J Bone Rep Recommendations. 2016, 2:3.
Copyright: © 2016 Mbamalu ON, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Osteoarthritis; Disability; Cartilage; Knee brace; Polycentric knee; Therapeutic modalities; Connective tissue
Osteoarthritis (OA) is one of most common forms of arthritis and is responsible for a huge burden of pain and disability . Osteoarthritis is characterized by both degeneration of articular cartilage and simultaneous proliferation of new bone, cartilage and connective tissue . It is the most prevalent form of arthritis and is the principal cause of disability in the elderly [3-6]. The area of local damage occurs in those parts of the joint subjected to maximal mechanical Stretch .
The OA of the knee is a common medical condition that is often seen in general practice and the second leading cause of disability, in which 10% are males and 13% are females affected . In Asia, prevalence rates of osteoarthritis knee were found to be high, approximately 6% of the population of 30 years or older and 12% of the population aged 65 years or older has osteoarthritis of knee [9,10].
Patients with osteoarthritis of knee usually present with major involvement in one compartment, with the medial compartment involved nearly 10 times more often than the lateral compartment may be due to medial compartment of a normal knee joint bears approximately 70% of body weight whereas the lateral and patella femoral compartment bears the remaining weight .
The patients with osteoarthritis of the medial compartment often have progressive loss of cartilage and joint space in this compartment, typically resulting in various alignments, which cause the mechanical axis/ground reaction force vector to pass more medially to the knee joint centre during gait. This result in increased loads across the medial compartment . Whereas in the lateral compartment generally have a valgus alignment and the mechanical axis and load bearing passes through the lateral compartment. Misalignment increases risk and progression of osteoarthritis of knee and results in decline in physical function .
The radiological classification of knee osteoarthritis, according to Kellgren-Lawrence Grading System , is based on x-rays and consists of normal, Grade I, Grade II, Grade III and Grade IV. Grade I is unlikely narrowing of the joint space, possible osteophytes, Grade II is Small osteophytes, possible narrowing of the joint, Grade III is Multiple moderately sized osteophytes, definite joint space narrowing, some sclerotic areas, possible deformation of bone ends and Grade IV is Multiple large osteophytes, severe joint space narrowing, marked sclerosis and definite bony end deformity .
The osteoarthritis progressively affects the aging population in the world in about 10% people . Presently, there are no pharmacological agents for the prevention or treatment of OA; the only medical option for OA involves pain management. In this context, cartilage tissue engineering has not held the high promises of therapy in OA  and the potential for cartilage regeneration through stem cell therapy has not yet fully materialized . Accordingly, total joint replacement, though expensive, is considered a final option for relieving pain and regaining function in patients with OA .
The Articular cartilage is thought to have limited regeneration potential. However, it has been observed that symptomatic pain relief and cartilage regeneration are possible in OA joints that have been surgically pulled apart or distracted for prolonged periods of time . This might have been a clue that cartilage regeneration is possible in OA joints. However, the mechanism by which cartilage growth might occur in the distracted joint space is not well known.
Mechanical factors are involved in the development and progression of osteoarthritis. If "loading" is a major cause in development and progression of osteoarthritis, then "unloading" may be able to prevent progression. There is evidence that unloading may be effective in reducing pain and slowing down structural damage. The unloading by bracing (nonsurgical), unloading by osteotomy (surgical) and unloading by joint distraction are the alternative methods of management of OA. Many reviews in these three fields have been published over the past few years. Recent studies argue for the usefulness of a biomechanical approach to improve function and possibly reduce disease progression in osteoarthritis [20,21].
A wide variety of other managements are available such as weight reduction, hydrotherapy, footwear and walking aids, other rehabilitation measures, physical therapy, systemic drug therapy, intra-articular drug therapy and surgery [22-28]. In addition to the consequences for the patient, it forms a considerable burden for society because of its chronic course and the high costs of interventions, especially in the context of socioeconomic status of our country. Therefore, the current managements for osteoarthritis of knee are targeted to alleviate pain by attempting to correct mechanical misalignment of the knee joint .
We report on a clinical trial of osteoarthritis of the knee treated with polycentric knee brace, by analysing the pain, stiffness, physical activity through WOMAC (Western Ontario McMaster universities Osteoarthritis Index) and radiological evaluation of the joints after 1 year use of polycentric knee hinged brace to patients with varying grades osteoarthritis of the knee in our setup.
It is a prospective study which was conducted in Nepal Medical College, Kathmandu, Nepal from September 2009 to August 2012. The study included total of 310 patients, 83 (26.77%) male and 227 (73.22%) female, who did not get satisfactory results with conservative treatments and having grade II, III and IV radiological changes in knees. Those patients who had fixed flexion and various deformity more than 10 degree, having significant hip, back or contralateral leg symptoms and physical or mentally inability to comply with the requirements of wearing braces were excluded from the study. Among 310 patients, 56 (18.07%) had grade II, 232 (74.84%) grade III and 22 (7.09%) grade IV osteoarthritis of knees which were diagnosed clinically and radio logically (Chart 1).
All the patients were initially examined by expert orthopaedic surgeons in outpatient department including the assessment of range of motion and wasting of quadriceps muscle. They were advised for AP (standing view) and lateral views to evaluate the radiological grading of the osteoarthritis changes in the respective knees. Once they were diagnosed, they were given the treatment options with their benefits and disadvantages. After evaluating the nature of the work, living standard of the patient, all the patients were thoroughly counselled regarding the proper application of the brace, duration of use of the brace, its mode of action, benefits of regular knee exercises. Then the patients were sent to Sir John Wilson Prosthetic & Orthotic centre for manufacturing tailor-made polycentric knee brace after the ethical approval. Once the patients were fully satisfied, the proper measurements were made for custom made polycentric knee brace regardless of the joint involvement. The patients were again asked to visit the centre where the patients were thoroughly taught how to apply the brace into their affected knees. They were also given a leaflet mentioning the steps of application of the brace with images. Immediately after the application of the brace, the patients were asked to use for average of 12 h per day and to go the physiotherapy department to learn the knee exercises to be done on regular basis and was supplemented with analgesics. The brace were used for average of 12 h per day and all the patients were instructed to go for regular physiotherapy. The polycentric knee brace is simple weight bearing device consisting of a mechanical joints over both sides of the knee with side bars attached to two plastic flaps (made of 4 mm Polypropylene) which in turn are provided with Velcro straps. The plastic flaps meant for the snugly fit into thigh and upper legs are made by moulding technique and cushioned inner side with 3 mm of Ethaflex. The thigh plastic flap is further moulded over the lower and medical part so that flap could snugly fit over the condyle to prevent slipping of the device while walking.
The technique of the polycentric knee brace is to transfer the weight from the anatomical knee joint to polycentric knee joint, to prevent further deformity and to decrease pain. The brace is to be worn externally from the ventral surface of the lower limb adjusting the mechanical knee joint exactly parallel to the anatomical knee joint and the Velcro straps are snugly tightened so that the brace does not become loose and slips out while walking This device is light in weight, cost effective and the manufacturing process is simple (Figure 1).
The patients were followed up at 6 weeks, 3 months, 6 months and 1 year, where the clinical findings were recorded, tabulated and analysed by WOMAC, there were 5 questions relevant to “pain”, 2 “stiffness” and 17 “physical function” and point 0 represents lightest symptoms and point 4 the severest symptoms for each questionnaire. That means total score of the severest symptom for “pain” will be 20, for “stiffness” will be 8 and for “physical function” will be 68 and consequently “total” will be 96, score for each category and for “Total” will decline when the symptoms is improved. The radiological findings like deformity correction and change in joint space were also viewed during the subsequent follow up.
The mean age was 64.2 years (50-82) and weight was 70.85 kg (50- 90). The joint involvement were 67 (21.66%) in left, 36 (11.61%) in right and 207 (66.77%) in B/L joints. 211 (68.06%) patients had various deformity and none of them had valgus deformity. The 37 (11.93%) patients had taken Injection Steroids prior to treatment, as their pain was not improved. so, polycentric knee brace was used. The polycentric knee brace was mainly given to osteoarthritis grade II (56) and III (232) (18.07% and 74.84%), and 22 (7.09%) had osteoarthritis grade IV as they were given the choice of arthroplasty but they refused to go for surgery due to financial crisis and lack of expertise, they were provided knee brace as a trial. The clinical findings were recorded, tabulated and analysed by WOMAC score and the radiological findings like deformity correction and change in joint space were also viewed during the subsequent follow up.
When evaluated all the patients after one year, 263 (84.83%) patients were still using the brace and 47 (15.16%) had discontinued the use of brace after some months and lost in follow up. There was improvement of pain and physical function in 96.29% (n=52) in grade II, 85.34% (n=198) in grade III and 13.63% (n = 3) in grade IV of OA Knee. There was 54% improvement in the Womack score, which was 78 ± 13 initially and later it decreases to 26 ± 9 after the use of polycentric knee brace in a 1 year follow up (Table 1) probably due to decrease in compressive loads transmitted to the joint surfaces in the knee compartment (Figure 1).
|WOMAC||Pain ( 20 )||Stiffness (8)||Physical Function (68)||Total Score (96)|
|Pre Brace||16 ± 4||3 ± 4||59 ± 5||78 ± 13|
|6 weeks||13 ± 7||2 ± 4||47 ± 8||62 ± 19|
|3 months||13 ± 6||2 ± 3||38 ± 6||53 ± 15|
|6 months||8 ± 5||1 ± 3||26 ± 6||35 ± 14|
|1 year||4 ± 3||1 ± 2||21 ± 4||26 ± 9|
Table 1: WOMAC scoring of pre brace and subsequent follow up.
It showed symptomatically relieved pain, stiffness and improved physical function in grade II and III osteoarthritis whereas prevented further radiological deterioration in all grades of osteoarthritis knees. Radio logically there was improved in few cases but it was almost identical in the radiographs taken before bracing (0.6 ± 0.4 mm; range 0.2–1.7 mm) and after the use of brace in a 1 year follow up (0.7 ± 0.5 mm; range 0.4-1 (Figure 2).
However some patients, 18.7% (n=58) complained of mild brace discomfort, loosening of the brace was seen in 26 patients and skin irritations (n=38) in initial stage of manufacturing the brace. There was damage of the teeth in 36 patients, which was repaired (Chart 2). The brace was continued after proper counselling and correcting the technical defect in the brace.
In our population, patients expect pain relief, improved function and activity level during the course of treatment. Apart from pain and physical activity it was also important to avoid future degeneration of the knee and able to maintain the activity of life. The polycentric knee braces decreased pain in the two to three weeks of time (average 2 weeks) following bracing and maintained improvement throughout the study. The clinical improvements of 54% in the WOMAC score reported in this study are consistent with previous studies that have examined the effects of knee braces on patients with Osteoarthritis (Chart 3).
Initially there were loosening of the braces, the teeth of joint used to get damaged in few months of time (average 4 months) and the patient used to complain itching while using the brace for a longer time especially in summer sessions. Gradually the technicians started making the moulded brace, higher quality of hinge joint could be imported and the patients were instructed to use the talcum powder, body lotion, coconut oil to overcome to itching problem.
Our  patients were not getting relief of pain by taking varieties of pain killer tablets and by doing physical exercises and were having grade III radiological changes. Most of them were socioeconomically poor, not able to bear the higher cost of surgery. They preferred to go for using polycentric knee brace and regular physical exercises. They were followed after 3 months. X-rays were done in all the patients. Some radiological changes (widening of the joint space) were found in seven patients and no further radiological damage of the joint were found in rest of the cases, although there was symptomatically relief of pain and improved function. They continued using the brace and were asked whether they would prefer to for surgery at minimal cost by visiting overseas team. All of them refused to go for surgery and were happy to continue the use of brace for few more months.
Tiku and Sabaawy  reported that cartilage regeneration is possible in OA joints that has been surgically pulled apart or distracted for a prolonged period of time.
Koshima et al. also documented regeneration of articular cartilage after high tibial valgus osteotomy for medial compartmental osteoarthritis of the knee joint. Widening of the joint space in seven patients in our study might be due to cartilage regeneration by prolonged distraction of the joint by regular use of knee brace .
Polo et al. reported 33 % improvement in the WOMAC score . Similarly, Kirklees et al. reported a 20–30 % improvement in the WOMAC score over 3–6 months of brace usage . A recent review by Beaudreuil et al.  found 16 studies of unloadingknee braces. Unfortunately, these studies were of poor quality and the recommendation for using an unloading-knee brace was again based on the Kirklees study. However, the review found short-term and mid-term benefits for pain and disability with the effectiveness of unloading-knee braces higher than that with neoprene knee sleeves and a short-term improvement in quality of life. The studies have also shown unloaded braces to be effective in not only reducing symptoms but also in shifting the weight bearing load. Other studies have also reported statistically significant improvements in clinical outcome as a result of brace usage, using outcome measures such as the visual analogue pain score or Hospital for Special Surgery Score.
In early stage of osteoarthritis of the knee, involving either medial or lateral compartment, simple unloading - knee brace with mechanical hinge joint over the medial or lateral side of the joint is commonly used. But, in our study, we used moulded brace with mechanical hinge joints over the both side of the knees irrespective of the compartment involved which helped the patients with more comfort.
The treatment of osteoarthritis of knee with a polycentric brace can provide significant improvement in pain, stiffness and increased physical activity levels and no radiological deterioration with few complications. The polycentric knee brace can be a costeffective alternative to the other treatments of osteoarthritis of the knees. However, the knee brace should not be used alone, but in addition to other therapeutic modalities.
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