Ankle Arthritis





KEY FACTS





  • The most common etiology of ankle arthritis is posttraumatic.



  • The ankle bears the highest load per surface area of any joint in the body, yet has a small surface contact area of only 350 mm².




    • The cartilage in the ankle is thinner than in the hip and knee.




  • The ankle joint is highly congruent, and its cartilage is uniform and stiff, allowing it to withstand high forces.




    • Any incongruency or loss of surface area leads to increased contact pressures and the development of arthritis.




  • Pain is the most common presenting symptom and is characteristically deep in the anterior ankle or dorsal foot.



  • Physical examination should include areas of skin and soft tissue condition (including calluses and scars) tenderness, alignment, range of motion, palpation of pulses, and sensory testing.



  • Nonsurgical options for the treatment of ankle arthritis include activity modification, bracing, medications, and injections.



  • Many surgical options for the treatment of ankle arthritis exist, including debridement, osteotomies, distraction, partial or total allograft replacement, fusion, total ankle replacement (TAR).



  • Ankle fusion is considered the “gold standard” treatment for ankle arthritis.




    • Fusion results in good or excellent results in 90% of patients at long-term follow-up.



    • The late development of adjacent joint arthritis remains a problem and has been the major impetus for the development of motion-preserving techniques for treating ankle arthritis.




  • TAR conserves motion at the ankle with potential, though unproven, benefits of improved gait and function and decreased incidence of adjacent joint arthritis.







Early ankle arthritis is shown. Anterior osteophyte with joint space preservation is a good candidate for anterior debridement.








AP radiograph of end-stage ankle arthritis with joint space narrowing osteophyte formation and subchondral cysts is shown.








Lateral radiograph of end-stage ankle arthritis shows joint space narrowing and anterior and posterior osteophytes and subchondral cysts.








Distraction arthroplasty is shown. Photograph shows the leg in the Ilizarov external fixator frame.






Posttraumatic





  • Posttraumatic causes account for ~ 50% of ankle arthritis cases.




    • Arthritis correlates with fracture type, degree of cartilage injury, and incongruity of the articular surface.




  • Radiographic evidence of arthritis is usually apparent within 2 years of injury in high-energy injuries.




    • However, in many cases it may be decades before pain becomes severe.




  • Arthritis occurs after ~ 14% of ankle (malleolar) fractures.




    • Weber C (proximal) fractures have a higher rate of arthritis (33%), as do trimalleolar fractures.



    • Maintaining fibular length and reduction of the posterior malleolar fragment improve outcome.



    • Larger posterior malleolar fragments involve a greater proportion of the articular surface and accordingly result in a higher rate of arthritis.




  • Unreduced syndesmotic injuries are a common cause of posttraumatic arthritis.




    • Because most Weber C injuries include syndesmotic disruption, failure to adequately reduce the syndesmosis may have accounted for the higher rate of arthritis with these injuries in the past.



    • Widening of the syndesmosis by 1 mm increases peak contact pressures in the ankle by 50%.




  • Pilon fractures are a higher energy injury and often result in increased rates of cartilage injury.




    • Consequently, there is a higher rate of arthritis, avascular necrosis (AVN), and complications.



    • Soft tissue injury may also be extensive and compromise healing both in the acute setting and following future surgical procedures.




  • Early range of motion may decrease the risk of arthritis, but there is little evidence to support this theory.



  • Talus fractures are less common but result in rates of posttraumatic arthritis as high as 50-97%.




    • The risk of AVN is also high.



    • AVN is the cause of much of the reported arthritis after talar fractures.



    • The talus is particularly prone to AVN because of its tenuous blood supply and predominately cartilaginous surface.




  • Osteochondral lesions of the talus typically do not lead to severe arthritis.




    • Although they can cause pain, they typically involve a small surface area.



    • The natural history of osteochondral lesions, whether small or large, is not well documented.






Biology of Ankle Cartilage





  • The ankle bears the highest load per surface area of any joint in the body yet has a small surface contact area of only 350 mm².



  • The ankle bears up to 5x the body weight with normal walking.



  • The cartilage in the ankle is thinner than in the hip and knee.




    • Thickness of ankle cartilage measures 1.0-1.7 mm.



    • Thickness of hip cartilage ranges from 1.4-2.0 mm.



    • Thickness of knee cartilage ranges from 1.7-2.5 mm.




  • The ankle joint is highly congruent, and its cartilage is uniform and stiff, allowing it to withstand high forces.



  • In the normal situation, this congruency keeps the contact pressures at an acceptable level.




    • But if the surface area of the joint is decreased or the congruency is lost, then the pressures rise quickly, leading to arthritis.



    • This is in contrast to the knee, where slight incongruencies can be compensated for by the menisci.






Evaluation of Arthritic Ankle


History and Physical Examination





  • Pain is the most common presenting symptom and is characteristically deep in the anterior ankle or dorsal foot.



  • History should include any previous trauma or infection, history of systemic disease, such as diabetes or inflammatory arthritis, previous treatments, shoewear, use of orthotics, and tobacco use.



  • Physical examination should include areas of tenderness, alignment, and range of motion.




    • Assessment of alignment of the ankle and hindfoot is particularly important.




      • The presence of severe deformity changes treatment options.




    • Most patients with severe arthritis will have lost the majority of ankle motion.




  • The presence and location of calluses may point to underlying deformity or malalignment, while scars are evidence of previous trauma or surgery.



  • Observation of the appearance of the soft tissues, palpation of pulses, and monofilament sensory testing provide additional information about healing potential.




    • If pulses are not palpable, vascular assessment is needed.



    • If any signs of neuropathy are found, the source of the neuropathy must be identified.




  • Examination of the foot, as well as the ankle, can yield additional useful information.




    • Hindfoot flexibility, stability, and alignment should be noted.



    • Arthritis at adjacent joints may require concurrent treatment to obtain relief of symptoms.




  • Gait analysis in patients with ankle arthritis typically shows decreased velocity, stride length, and cadence and more time in double-limb stance.




    • However, a formal gait analysis is generally not required in the work-up of ankle arthritis.




Imaging





  • Radiographs should include weight-bearing anteroposterior, lateral, and mortise views of the ankle as well as anteroposterior, lateral, and medial oblique views of the foot.




    • Radiographs should be assessed for joint space narrowing, alignment, and bone quality.



    • The location and size of osteophytes should also be noted, especially when impingement is suspected.



    • Obtaining a weight-bearing film is critical to assess true deformity and joint space narrowing.




  • Alignment should be evaluated on both sagittal and coronal views.




    • A procurvatum or recurvatum deformity may be noted by examining the relationship of the tibia to the talus, which should be centrally located with its lateral process under the midline of the tibia.



    • In the coronal plane, varus-valgus alignment should be at ~ 0°, measured by the intersection of the midtibial line and the talar dome.




  • Specialized views may be useful in certain patients.




    • The weight-bearing hindfoot alignment view shows coronal alignment of the hindfoot.



    • The Harris view shows axial alignment of calcaneus.



    • The Broden view shows the subtalar joint.




  • Other imaging modalities are generally not needed for diagnosis and surgical planning unless diagnosis is in doubt.




    • Bone scans may identify occult arthritis, stress fracture, infection, or reflex sympathetic dystrophy.



    • Computed tomography (CT) can be used to identify a subtle syndesmosis injury and for complex fractures.



    • Magnetic resonance imaging is most useful for investigating the soft tissues, such as in cases of infection and tumor.




Other Diagnostic Modalities





  • Selective diagnostic injections of local anesthetic, such as lidocaine, may be injected in the ankle and adjacent joints to determine relative contributions to symptomatology.




    • For example, pain from subtalar arthritis may be confused with ankle-related pain and may be clarified with selective injections to aid surgical planning and improve outcome.




  • Laboratory data are generally not helpful in diagnosing ankle arthritis.




    • However, if there is concern for infection, complete blood count, erythrocyte sedimentation rate, and C-reactive protein are sensitive indicators.






Nonsurgical Treatment


Activity Modification and Bracing





  • Activity modification may minimize the pain of ankle arthritis.




    • Steps include recommending low-impact activities, such as swimming and stationary bicycle, over high-impact exercise, such as example jogging, and sedentary work over occupations that require prolonged standing.




  • Weight loss may also alleviate symptoms by decreasing force across the joint and may improve results of future surgical procedures.



  • A cane carried in the contralateral hand may partially offload the joint.



  • Shoe modifications, orthotics, and braces can also be used to temper the pain of an arthritic ankle.




    • A shoe with a rocker sole may allow more comfortable gait by decreasing the amount of ankle motion needed.



    • A high-top shoe, boot, or lace-up ankle brace can provide some support and immobilization of the ankle.



    • An ankle-foot orthosis also immobilizes the ankle joint, improves axial alignment, and can improve gait.



    • An offloading brace that transfers load away from the ankle and to the patellar tendon and proximal tibia can be used in extreme situations.




      • However, these braces are bulky and cumbersome.





  • Casting may be viewed as the ultimate brace for the ankle and offers pain relief by immobilizing the ankle joint.




    • A short leg walking cast can be used for 6 weeks to reduce inflammation and pain, although postimmobilization stiffness should be expected.




Medications





  • Medications may also be used to relieve the pain and inflammation of ankle arthritis.




    • Nonsteroidal antiinflammatory drugs act by blocking cyclooxygenase to limit prostaglandin production and thus inflammation.




      • They also have a central effect, which is responsible for their analgesic action.





  • Glucosamine is a building block of proteoglycans, the primary component of cartilage matrix.




    • Although data are limited and primarily addresses osteoarthritis of the knee, it has been shown to offer some pain relief to patients and result in decreased inflammation in arthritic joints.




  • Glucosamine is commonly coupled with chondroitin, another cartilage matrix protein, and sold as an over-the-counter supplement in a largely unregulated fashion.




    • Quantity and bioavailability of the active agents in these preparations is largely unknown.




  • Steroid injections may be used in the ankle and adjacent joints to decrease inflammation and alleviate pain.




    • The ankle joint is injected via the medial or lateral gutter with the needle directed posteriorly.




  • Steroid injections have been shown to be beneficial for short-term pain reduction but are no different from placebo in the long term.




    • Repeated injections separated by several months continue to be effective in some patients but often show diminishing returns.



    • Complications include a low risk of infection and skin depigmentation.



    • There is evidence from hip and knee arthroplasty that recent steroid injection can increase the risk of infection during subsequent joint arthroplasty.




  • Hyaluronic acid injections in the ankle may be helpful for pain relief, although the evidence is not strong.



  • There is no clinical evidence to support the use of platelet-rich plasma injections for ankle arthritis, although that is being explored by some physicians.





Surgical Treatment


Debridement





  • Debridement of the ankle, either open or arthroscopically, has been advocated for treatment of ankle arthritis in certain cases.




    • The ideal patient has a specific indication, such as hypertrophic synovium, loose body, or impinging osteophytes, with relatively preserved joint space.



    • Small chondral lesions, < 1 cm, may also be treated effectively with debridement and drilling.



    • Results of debridement in generalized arthritis with joint space narrowing or deformity are poor.




  • For arthroscopic debridement, the anteromedial and anterolateral portals are used as the working portals.




    • Care must be taken to avoid injuring neurovascular structures near the portal sites, particularly branches of the superficial peroneal nerve.




  • Arthroscopy allows removal of loose bodies, debridement of hypertrophic synovium, drilling of osteochondral defects, and removal of impinging osteophytes.




    • However, treatment of extensive osteophyte complexes may not be possible through an arthroscopic approach and may require an anterior approach to the ankle joint.



    • Impinging bone should be removed to provide an anterior tibia to talar neck angle of > 60°.




  • In one older series of 57 patients, 70% good or excellent results were achieved with arthroscopic treatment of synovitis, loose bodies, or osteophytes, compared with only 12% in patients with generalized arthritis.




    • Furthermore, 75% of these arthritic patients went on to fusion or other further surgical treatment after debridement.




Osteotomy





  • After fibular fracture, if the distal fibula is not anatomically reduced, instability and resultant arthritis can occur.




    • The fibula is most often shortened and externally rotated, allowing abnormal subluxation of the talus.



    • These patients may present late, after fracture healing, with persistent pain.




  • Radiographs may show decreased overlap of the distal fibula and anterior tibia on the anteroposterior view or widening of the tibiofibular clear space on the mortise view.




    • Comparing radiographs with the contralateral ankle or obtaining a CT scan of both ankles may identify subtle injuries.




  • Fibular osteotomy may be indicated in these patients with fibular malunion and pain to restore fibular length and ankle stability.




    • The goal of fibular osteotomy is seating of the distal fibula into the incisura fibularis and restoration of a symmetric joint space.



    • Fibular osteotomy as an isolated procedure, however, is contraindicated when there is joint space narrowing of the ankle, indicating that extensive cartilage damage has already taken place.




  • Distal tibial osteotomy may be useful in certain circumstances.




    • The tibial osteotomy is usually a medial or lateral closing wedge with internal fixation.



    • It is most useful for angular deformities with loss of joint space on the medial or lateral side of the joint.



    • With realignment, weight-bearing forces are more evenly distributed to the unaffected side of the joint.




  • Short-term results of distal tibial osteotomy are generally good for the rare patient with the correct indication.




    • However, as in the knee, the surgeon should expect arthritis to slowly worsen with time.




Distraction





  • Distraction arthroplasty is a possibility for a minority of patients with ankle arthritis.




    • The theory is that by distracting and offloading the joint for 3 months, symptoms will reduce, and the cartilage may actually repair itself.




  • A thin-wire (Ilizarov) external fixator is placed across the ankle in distraction.



  • The technique is based on data from animal studies in which immobilization and distraction reduce mechanical forces across the joint while maintaining intraarticular flow and pressure.




    • Because chondrocytes depend on diffusion for nutrition, maintenance of intraarticular flow without mechanical stress may promote enhanced repair of cartilage.



    • There are, however, no human data showing cartilaginous repair, and animal data show only suggestive evidence.



    • Alternatively, the technique may enhance joint space and relieve symptoms by increasing fibrosis of the joint.




  • The technique is generally used in younger patients who prefer an alternative or temporizing measure prior to fusion or arthroplasty.




    • Perhaps the best candidate is a young person with severe arthritis but preserved ankle motion (for whom fusion would not be ideal).




  • The technique has been limited to patients with posttraumatic or primary arthritis, as previous reports in patients with inflammatory arthritis of the hip showed poor results.



  • Relative contraindications include an infected or a neuropathic joint and inflammatory arthritis.




    • Although deformity may be addressed by Ilizarov technique, simple distraction does not affect alignment and should not be used as an isolated treatment in a severely deformed joint.




  • Most importantly, the Ilizarov technique requires a committed and compliant patient and a watchful surgeon.



  • The surgical technique for placement of the Ilizarov external fixator and an outline of treatment is provided below.




    • Proximal and distal tibial rings are placed first, followed by a half-ring around the heel with calcaneal wires, a half-ring over the forefoot with metatarsal pins, and a wire through the talus and attached to the foot frame to prevent subtalar distraction.



    • Distraction may be accomplished acutely in the operating room or by distracting 0.5 mm 2x daily until 5 mm total of distraction is achieved.



    • The frame is then worn for up to 3 months with weight bearing generally allowed after the first 1-2 weeks.



    • The frame may be adjusted to concurrently correct equinus deformity.



    • Angular deformity correction with an Ilizarov frame generally requires osteotomies.




  • Patients require a special shoe secondary to rigidity of the foot and ankle and must perform careful pin care and skin checks.



  • Common complications include pin site infections requiring oral antibiotics and pin breakage.



  • The goals of ankle joint distraction are relief of pain through widening of the joint space.




    • A single report did show increased joint space after distraction, but this finding has not been consistent.




  • However, even if joint space and range of motion are not improved, a handful of case series show patient satisfaction in 2/3-3/4 of patients with better functional scores over time.




    • This implies a progressive improvement of symptoms after completion of the distraction.




  • Approximately 1/4 of patients require fusion within 1-2 years.



  • One study of 17 patients randomized to arthroscopy or distraction showed improved symptom relief in the distraction group.




    • This study was limited by a small sample size, lack of blinding, and poor control treatment (as arthroscopy has limited benefit in generalized arthritis).




  • In summary, distraction arthroplasty shows promising preliminary results in young patients with severe degenerative joint disease.




    • Although it is unclear whether joint space expansion is maintained or whether cartilage repair is actually taking place, patients report improvement in the majority of cases and continue to see improvement with time, at least in 2- to 5-year follow-up.



    • Additionally, distraction does not preclude future arthrodesis or arthroplasty.



    • However, this technique does require a relatively sophisticated patient and committed surgeon to carefully monitor the somewhat difficult and complex Ilizarov frame.




  • Distraction arthroplasty remains a viable option because of the lack of good surgical options for the younger patient with arthritis.



Allograft





  • Fresh osteochondral allografting is another technique that offers promise to younger patients with severe ankle arthritis who wish to delay or avoid the functional limitations of arthrodesis.



  • The technique uses a fresh cadaveric specimen to resurface the tibial plafond and talar dome with full-thickness cartilage and a thin layer of underlying bone that reliably integrates into the host bone.



  • Fresh allografts offer a distinct advantage over frozen grafts used in tumor reconstructions in that the damaged articular surface is resurfaced with viable chondrocytes.




    • Limited 2nd-look arthroscopy and retrieved specimen data have shown viable chondrocytes several years after implantation.




  • Allografting of the arthritic ankle generally includes resurfacing the entire joint, but smaller allografts may be used for osteochondral lesions or focal AVN.



  • Fresh allografts are harvested based on standard tissue procurement guidelines.




    • Tissue is procured within 24-48 hours and stored in enhanced media.



    • Tissue is then matched to a recipient based on size and transplanted within 2-5 weeks.



    • Previously, tissue was transplanted within 7 days, but recent safety concerns have led to a 14-day holding period for microbiologic testing.



    • No tissue matching or postoperative immunosuppressive therapy is currently employed.




  • As with distraction, fresh allografts offer promise as a temporizing measure or potential alternative to fusion or implant arthroplasty in young, active patients with severe ankle arthritis.




    • Published studies have limited recipients to those under 55 years of age.



    • Obesity is also a relative contraindication, as allografts may be unable to tolerate the increased mechanical stress, particularly during early incorporation.



    • Osteochondral allografts, like other bone graft materials, should not be placed in the setting of infection.



    • Severe bone loss and malalignment are also relative contraindications to allografting.




  • The technique of fresh osteochondral allografting of the ankle borrows concepts from total ankle arthroplasty and tumor surgery.




    • A temporary external fixator is first placed to allow joint distraction during allograft placement.



    • An anterior approach to the ankle gives wide exposure of the tibiotalar joint, as in total ankle arthroplasty.



    • The surgeon then resects the distal tibia and talus, adjusting as indicated to correct mild angular deformity.



    • Total ankle allograft cutting jigs may be used to improve precision of the resection.



    • A size-matched allograft is then cut appropriately and fixed into the defect.




  • The patient should be assessed preoperatively to determine if an Achilles lengthening or gastrocnemius recession is required as well.



  • Patients are generally kept non-weight bearing for 3 months during recovery to allow incorporation of the graft.



  • A number of complications of fresh osteochondral allografting have been reported, including graft collapse, fracture, and tissue rejection.




    • Collapse of the subchondral bone may occur, especially with heavier patients or thin grafts.



    • Graft thickness must be balanced between the risk of collapse and a potential infectious or immunogenic risk from thicker grafts.




  • No incidence of infection or disease transmission from an osteochondral allograft has been reported, although risk is probably equivalent to that of blood transfusion.



  • The majority of allograft recipients show humoral cytotoxic antibodies indicative of an immune response to the foreign tissue, but no immune reaction has been noted in histologic examination of retrieved specimens.



  • There is a risk of intraoperative or late fracture of the medial malleolus, which must be carefully preserved when making the tibial cut.



  • Case series generally show 2/3-3/4 of the patients will have a good result.




    • Risk factors identified as leading to poor outcome included graft-host mismatch (graft too small) and graft thickness < 7 mm (graft too thin).




  • In summary, fresh osteochondral allografting of the ankle represents a promising technique for young, active patients with severe ankle arthritis who are unwilling to accept the functional limitations of arthrodesis.




    • Good results have been reported in long-term follow-up of allografts in the knee, but limited data are available for total resurfacing of the ankle.



    • When compared with implant arthroplasty, allograft replacement of the ankle better preserves bone stock.



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Oct 29, 2019 | Posted by in ORTHOPEDIC | Comments Off on Ankle Arthritis
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