Osteoarthritis presents less commonly in the ankle than in other lower limb joints. This is, perhaps, surprising, as the stresses in the ankle are high and the joint surfaces area lower than in other joints. In the ankle OA is often, but not always, secondary.
Main causes of ankle OA in our population
- Post-traumatic arthritis . These patients are often younger and have only one joint involved. They may still hope to return to an active lifestyle including contact or extreme sports, which may have precipitated their injury in the first place, and may be intolerant of residual restrictions or discomfort. Some have quite significant deformities or bony defects that preclude replacement or simple reconstruction; may have had open fractures, wound problems or infected pin tracks that predispose to infection; or nerve injuries or regional pain syndromes that limit the improvement that can be expected from treating their arthritic joints.
- Rheumatoid arthritis and other inflammatory diseases such as psoriatic arthritis, where the inflammatory component has burnt out leaving a damaged joint. These patients often have several joints involved, and may have other joint replacements. They tend to be less mobile and more disabled than patients with other conditions listed below. Rheumatoid disease can affect immunity, renal and pulmonary function and the patients are often anaemic. Many second line drugs also affect immunity and may affect wound healing and increase the risk of infection after surgery.
- Primary osteoarthritis . This is probably commoner than formerly believed. Some of these patients have monoarticular or oligoarticular disease, remain fairly active and expect to continue doing so. Others have multiple joint involvement and in this sense are more like rheumatoid patients, but without the systemic effects.
- Intra-articular disease such as osteochondritis dissecans, osteonecrosis of the talus or synovial chondromatosis. Clinically these patients resemble the primary osteoarthritics but may have had several previous procedures, open or more commonly arthroscopic, which may leave complications and limit future options.
- Arthritis secondary to instability and/or foot deformity. A few patients have arthritis related not to an acute injury but to chronic instability; persistent ligamentous instability is likely to preclude ankle replacement. Major foot deformities such as pes cavus or severe flatfoot, or proximal malalignments such as a malunited tibial fracture, can lead to asymmetric loading of the ankle and/or ligamentous instability and subsequent arthritis. The abnormal biomechanics can preclude an ankle replacement, or require a preliminary realignment or stabilisation.
- Septic arthritis . The joint may be destroyed by sepsis which then limits the reconstructive options. These patients often require complex reconstruction.
Assessment
History
Most patients present with pain in the ankle. Sometimes it is described in the posterior foot or midfoot, or up the leg. Radiation above the mid-tibia should make one suspect proximal problems. Some patients complain the ankle locks or gives way, which may be due to a loose body but usually just represents attacks of severe pain with reflex inhibition of the supporting muscles. Midfoot pain may also arise from OA of the talonavicular, calcaneocuboid or lesser tarsal joints.
It is important to find out what has already been tried. It is quite common to see a patient referred for an ankle fusion or replacement who is not even taking regular analgesics. There may be several non-surgical options to explore, or the patient may have tried all these and needs counselling about definitive surgery.
As noted above, patients with arthritic ankles often have other joints involved, which may affect the surgical option and likely outcomes. Others have had a severe or repeated injury or infection, which may have affected their soft tissue envelope or left troublesome scars or nerve problems. A history of deep infection will restrict definitive surgical reconstruction possibilities – almost certainly to a fusion, possibly with an Ilizarov or other external frame.
Cigarette smoking increases the risks of ankle non-union by at least three times, and may affect wound healing after any procedure.
Examination
- Check other joints and limb alignment
- Look at the gait - most patients have an antalgic gait
- Examine the skin and soft tissues carefully for the effects of previous surgery, injury or infection
- Check the alignment of the tibia to the hindfoot, the midfoot and the forefoot. What is the overall foot shape? If there is malalignment, is it correctable or fixed – it may be correctable at some levels but not at others.
- Palpate for tender areas, synovitis, effusion and loose bodies. If there is anterior tenderness, dorsiflex the ankle while pressing in the tender area (the Molloy impingement test), looking for an impingement lesion.
- Assess the range of ankle motion; check that any dorsiflexion/plantarflexion is in the ankle rather than the midtarsal joint.
- Perform the anterior draw and talar tilt tests for instability.
- Check what movement remains in the subtalar and midtarsal joints.
- Assess circulation, sensation and power.
Investigation
The main investigation is a standing AP and lateral radiograph of the ankle. This will allow assessment of remaining joint space, spurs and loose bodies. If there is malalignment, a standing hindfoot alignment view will show at which level – ankle, subtalar or both – the malalignment is occurring.
Where there is loss of bone stock or complex anatomy post trauma or infection a CT can be helpful
MR will show joint surface lesions such as osteochondritis dissecans, and soft tissue abnormalities including infection and sinuses.
If there is osteonecrosis, usually of the talus, MR will show the extent of the abnormality, which will help surgical planning, but an isotope bone scan is required to show how much revascularisation has occurred.
Standard blood tests may be required to rule out inflammatory arthropathy, gout or residual infection.
After history, physical examination and appropriate investigation, it should be possible to decide whether
- The patient could try non-surgical treatment with a reasonable hope of controlling symptoms, at least in the short to medium term
- The patient has exhausted non-surgical treatment and some form of surgical treatment could be considered electively
- There is evidence of some serious underlying problem, usually infection,, which needs to be tackled urgently
If surgery is appropriate:
- The arthritis is relatively early, with some residual joint space and adequate alignment and bone stock - arthroscopic debridement may be worth considering
- There is end-stage arthritis which would require arthroplasty or fusion
- There is a complex problem which may require additional procedures such as debridement, massive bone grafting, multiple reconstructive fusion or the use of an Ilizarov frame
Non-surgical treatment
Most patients presenting with arthritic ankles can be managed with simple measures:
- Advice and reassurance on the relatively benign natural history of osteoarthritis, hurt doesn’t mean harm, keep fit and active etc
- Simple analgesics, NSAIDs, medium strength analgesics
- Improved control of inflammatory arthropathies, often with second-line drugs
- Some patients find it useful to wear boots rather than shoes, and sometimes splints or braces are useful to control symptoms
Steroid injections are often helpful on an empirical basis, although there is no good evidence base for their use and in other joints they may not be much better than placebo.
Hyaluronan supplementation injections have been described in other joints. In the knee the evidence suggests a modest effect in moderately severe arthritis but not in end stage disease. There have been anecdotal reports in the ankle.
Surgery is an option where non-surgical treatment has failed to control the patient’s symptoms and they are seriously affecting the patient’s activities of daily living, work and sleep.
Surgical options
- Arthroscopic debridement . Can be useful where the joint is reasonably well preserved, especially if the main problem is impingement from synovitis or spurs, or loose bodies. Arthroscopic debridement for impingement had a 75% success rate at 5 years in the presence of spurs, but only 50% with loss of joint space (Tol et al 2001). Ogilvie-Harris et al (1995) found limited improvement in about 2/3 of 27 patients.
- Distraction arthroplasty . An Ilizarov external fixation frame is applied across the ankle and a distraction force applied. The frame is articulated to allow active joint movement. Useful improvement in pain and movement have been reported (Marijnissen et al 2003). Weightbearing radiographs suggest that joint cartilage thickness is regenerated. This technique requires complex apparatus and specialised staff.
- Osteotomy of the distal tibia . Distal tibial malalignment may be secondary to injury, intra-or extra-articular or involving the growth plate; or it may be an intrinsic deformity. Realignment is an option where the joint is reasonably well preserved – an arthroscopy may be required to check. Where the joint is severely arthritic an arthrodesis or replacement is more appropriate.
- Arthrodesis . Until recently this was the only real option for end-stage ankle arthritis of whatever aetiology. The traditional British method was that of Charnley with a destructive anterior transverse approach and external fixation with a semi-stable frame. This had a high incidence of infection and non-union. Arthrodesis is now normally carried out with an open or arthroscopic surgical technique, and fixation with screws, plates or an intramedullary nail. Arthroscopic surgery does less soft-tissue damage. Early studies suggested a high rate of non-union, but in experienced hands it probably results in quicker and less complicated union of the fusion (O’Brien et al 1999). However, it is difficult in very stiff ankles with large osteophytes, or where there is significant deformity. Long-term studies show OA developing in adjacent joints, although not always symptomatic, and of course this might have happened anyway without the fusion.
- Total ankle replacement has been around for over 30 years. However, early prostheses did not reproduce the biomechanics of the ankle well and had a very high failure rate. Second-generation prostheses from the late 1980s onward introduced improved engineering, often with three components. 10-20 year results are now being published (Kofoed 2004, Buechel et al 2004), indicating success in over 90% of patients. However, these are the series of the designers of the various prostheses, and further results from the “real world” may not be quite so optimistic. The Wrightington series (Wood and Deakin 2003) is a realistic and critical account with 5-8 year follow-up and 92% 5-year success. Results in OA and RA are similar (Kofoed 2004, 1998; Wood and Deakin 2003). Ankle prostheses also seem to be best uncemented; the long term results of the STAR ankle have been significantly better in the uncemented design (Kofoed 2004). Like all joint replacements, failure occurs and may require revision replacement or fusion. The failure rate for revision arthroplasty is high and most patients will be better revised to a tibiotalocalcaneal fusion.
Replacement versus fusion for the end-stage arthritic ankle
It is only appropriate to compare fusion and replacement for patients without major deformity, infection, bone loss or neuropathy – these would only be candidates for fusion. However, there have been no direct comparisons of replacement and fusion in patients in whom both would be an option. In addition, outcome measures in single-procedure series are so varied that it is difficult to compare them.
As might be expected, ankle fusion affects the range of motion and kinematics more than does replacement, and certain designs are closer to normal than others (Valderrabano et al 2004a,b). Gait analysis is much closer to normal in replaced than in fused ankles (Butcher et al 2004). Hence it is plausible that ankle replacements would place less stress on other joints, both in the tarsus and proximally. Nevertheless, this requires clinical confirmation.
Clinical results of ankle fusion. A study of patients 20 years after ankle fusion (Fuchs et al 2003) reported reduced SF-36 pain, physical functioning and emotional disturbance scores, and moderate Olerud ankle scores. Most patients wore customised footwear, but few had walking aids. All but one had returned to work. There was significant progressive OA in the other hindfoot joints. The surgery included more external fixation than would be expected in a current population. Another study (Buchner et al 2003) reported little or no pain and restriction of activity in 92% of patients at an average of 9.3 years follow-up. An independent study of fusion in OA (Anderson et al 2002) found that the true fusion rate was 80-89% but the clinical and radiological outcomes were not the same. The longest follow-up of arthroscopic arthrodesis (Glick et al 1996) reported a 97% fusion rate at an average of 8years follow-up, with 88% good or excellent results. In rheumatoid disease, Felix et al (1998) reported union in 96% of 26 ankles at 2-8 year follow-up, and no pain 19.
Clinical results of ankle replacement. These studies tend to highlight need for revision as the main outcome measure. At 12 years, the survivorship of the current cementless Buechel-Pappas implant was 92% (Buechel et al 2004), but clinical results were presented only as excellent 88%, good 5%, poor 7% (75 patients). Twelve-year survival for the STAR ankle was 95%, with a mean Kofoed ankle score of 91.7/100. The long-term survival rate is based on small numbers in each study. The Wrightington series (Wood and Deakin 2003), although shorter in follow-up (2-8.5 years), is also worthy of study, as it is very large, meticulously critical and realistic. The 5-year survival rate was 92.7%. The mean AOFAS hindfoot score for pain improved from 0/40 pre-operatively to 35 at final follow-up and the functional score from 28/60 to 35. Complications and the learning curve are detailed. None of these studies comment on OA in adjacent joints.
There is not enough data to indicate whether fusion or replacement is to be preferred for patients in whom either procedure would be an option. At about 10 years clinical success rates appear similar; possibly the onset of OA in other joints reduces the success of fusion thereafter. The improved kinematics of ankle replacement probably reduce the wear on adjacent joints, and this could be important, particularly in patients with multiple joint pathology. The improved range of movement is anecdotally useful to patients, but there are no comparative studies.
References
- Akagi S, Sugano H, Ogawa R. The long-term results of ankle joint synovectomy for rheumatoid arthritis. Clin Rheumatol. 1997 May;16(3):284-90
- Anderson T et al. Arthrodesis of the ankle for non-inflammatory conditions: healing and reliability of outcome measurements. FAI 2002;23:390-3
- Buchner M et al. Ankle fusion attributable to post-traumatic arthritis: a long-term follow-up of 48 patients. CORR 2003;406:155-64
- Buechel FF et al. Twenty-year evaluation of cementless mobile-bearing total ankle replacements. CORR 2004;424:19-26
- Butcher CK et al. Gait analysis of patients with ankle replacements. Presented at BOFSS scientific meeting 2004
- Felix NA, et al. Ankle arthrodesis in patients with rheumatoid arthritis. Clin Orthop (1998); (349): 58-64.
- Fuchs S et al. Quality of life 20 years after fusion of the ankle. JBJS 2003; 85B:994-8
- Glick JM et al. Ankle arthrodesis using an arthroscopic method: long-term follow-up of 34 cases. Arthroscopy. 1996 Aug;12(4):428-34
- Marijnissen AC, et al. Clinical benefit of joint distraction in the treatment of ankle osteoarthritis. Foot Ankle Clin (2003); 8(2): 335-46
- Ogilvie-HarrisDJ, Sekyi-Otu A. Arthroscopic debridement for the osteoarthritic ankle. Arthroscopy 1995;11:433-6
- Nakamura H, Tanaka H, Yoshino S. Long-term results of multiple synovectomy for patients with refractory rheumatoid arthritis. Effects on disease activity and radiological progression. Clin Exp Rheumatol. 2004 Mar-Apr;22(2):151-7
- O’Brien TS et al. Ankle arthrodesis using an arthroscopic method: long-term follow-up of 34 cases. Arthroscopy. 1996 Aug;12(4):428-34
- Tol JL et al. Arthroscopic treatment of anterior impingement in the ankle. JBJS 2001;83B:9-13
Valderrabano V et al. Kinematic changes after fusion and total replacement of the ankle: Part 1: range of motion. FAI 2003;24:881-7
- Valderrabano V et al. Kinematic changes after fusion and total replacement of the ankle: Part 2: movement transfer. FAI 2003;24:888-96
- van der Zant FM, Jahangier ZN, Moolenburgh JD, van der Zee W, Boer RO, Jacobs JW. Radiation synovectomy of the ankle with 75 MBq colloidal 186rhenium-sulfide: effect, leakage, and radiation considerations. J Rheumatol. 2004 May;31(5):896-901
- Wood PLR, Deakin S. Total ankle replacement: the results in 200 ankles. JBJS 2003;85B:334-41
Patient information on ankle replacement (Wrightington unit)
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