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Arthrosis of the ankle and hindfoot

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Ankle  arthrosis commonly occurs after a major traumatic ankle injury such as a pilon fracture.  A depressed calcaneal (heel) fracture commonly leads to . A pilon fracture may cause arthrosis of the tibiotalar (ankle) joint; a depressed calcaneal can cause subtalar arthritis.  Arthrosis is also seen after less severe injuries, especially if those injuries cause malalignment. Unlike the knee and hip, the ankle joint is relatively uncommon site for the development of primary (idiopathic) osteoarthritis.  Arthrosis of the ankle is also treated differently than that of with methods that would not be used in the knee or hip, in that constraining as loss of motion to limit pain is fairly well-much better tolerated in the ankle. Thus, bracing and (in more extreme cases) surgical fusion is a commonly used methods of treatment.

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Treatment options and outcomes

The goals of treatment for ankle and hindfoot osteoarthritis are pain reduction, improvement in function, and increased range of motion. Treatments can be non-operative or operative.

Non-operative treatment

Non-operative treatment is indicated in certain cases of mild to moderate arthrosis. It normally involves oral non-steroidal anti-inflammatory drugs and/or analgesics, physical therapy, and ankle stabilization. General exercise and activity modification can also help to prevent pain and progression of symptoms. In severe cases, intra-articular corticosteroid or hyaluronic acid injection may be necessary to provide short-term pain relief.

Physical therapy is an important aspect of non-operative care early in the course of treatment.  It will not decrease the pain and symptoms, however, physical therapy can help the patient , to maintain range of motion, strength, and proprioception and thereby decrease the likelihood of leg atrophy over time. Exercise is helpful to may help maintain an ideal body weight because a high BMI can lead to excessive force on the affected joints. Activity modification and restriction of sports or high-impact activities can help the patient avoid painful activities and decrease pain from the involved arthritic joint. 

Ankle support is an important aspect of non-operative care that can minimize painful joint motion and relieve pressure points. There are many ankle support options ranging from simple over-the-counter shoewear modification to braces to custom-molded ankle-foot orthoses (AFOs).

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Operative treatment is indicated in patients with severe osteoarthritis and those in whom when conservative treatment has failed. Several different surgical options exist for the treatment of osteoarthritis.

Arthroscopy: Ankle/subtalar arthroscopy may be a helpful tool for some patients with painful ankle or handoff arthritis. Surgeons can visualize the joint and perform certain therapeutic procedures to target the source of pain including synovectomy, debridement of soft tissue impingement or meniscoid lesionsArthroscopic procedures include synovectomy, debridement, loose body removal, osteochondral lesion repair, excision of bone spurs, and chondroplasty.  Effectiveness has not been assessed in randomized controlled trial, however.

Tibial osteotomy: Some cases of ankle arthritis stem from a tibial deformity that leads to poor load distribution across the ankle joint. Tibial osteotomy can address the deformity and correct alignment, improving and improve load distribution across the ankle joint. It is indicated in young patients with a varus or valgus deformity and mild to moderate arthritis caused by a tibial deformity.

Ankle arthrodesis (Figure 9): Ankle arthrodesis (tibiotalar fusion) is one of the most predictable means of reliving severe pain from ankle arthritis. Arthrodesis is indicated in patients with painful ankle arthritis that has failed non-operative treatment. The  The fusion can be performed open or arthroscopically – fusion rates are similar between the two, but arthroscopy is associated with shorter hospital stays, less intraoperative blood loss, and shorter time to fusion. Fusion is generally achieved in 80-90% of patients. The optimal orientation for ankle fusion is neutral dorsiflexion/plantarflexion, 5 degrees of valgus, 5-10 degrees of external rotation, and a slight posterior displacement of the talus under the tibial plafond. The about 80 to 90%.  The major disadvantage of arthrodesis is that it sacrifices the plantarflexion and dorsiflexion movements of the ankle joint for pain relief. Additionally, the . The lack of ankle motion caused by the from fusion may be mildly impairing and may also accelerate arthrosis in the subtalar and other remaining joints of the hindfootjoint.

 

Figure: Ankle arthrodesis (ankle fusion). In order to maximize the motion in surrounding joints following fusion, the ankle should be positioned in neutral dorsiflexion and slight hindfoot valgus (heel angled to the outside). Credit: http://www.orthopaedicsone.com/display/Main/Ankle+arthritis

Total ankle arthroplasty (TAA): In this procedure, the surgeon replaces the damaged tibial plafond and talus with an artificial joint (Figure 10). It is ideal for a lightweight, sedentary, older patient with end-stage osteoarthritis who has minimal deformity, good range of motion, a good soft tissue envelope, and is unwilling to undergo fusion in the affected joint. Ankle replacements normally rely on proximal fixation in the tibia and subsequent proximal fixation in the tibia and fibula. Since the prosthesis will tend to fail over time, TAA is best for older patients who are relatively less active. 

 

Figure 10: Total ankle arthroplasty requiring syndesmotic fusion. Credit: http://www.orthopaedicsone.com/display/Main/Ankle+arthritis

Distraction arthroplasty: Distraction arthroplasty is based on the idea that arthritic cartilage will heal when the joint is unloaded. A ring external fixator is applied to produce mechanical separation of the opposing articular cartilage surfaces. This procedure has fallen out of favor in recent years.

Subtalar arthrodesis: Fusion of the subtalar joint (Figure 11) is the gold standard best treatment for extensive subtalar arthritis that has failed non-operative treatment. This procedure involves removing the joint cartilage and subchondral bone and fixating attaching the two sides of the subtalar joint with screws and bone grafts. The main goals are pain relief and restoration of talocalcanear alignment. This procedure sacrifices side-to-side motion at the subtalar joint for pain relief, but patients are generally able to be much more active due to significantly less pain.Again, the tradeoff inherent in any fusion procedure (loss of pain at the price of loss of motion) applies here as well.(The procedure can be extended to include the talo-navicular and calcaneo-cubiod joints; this is called a "triple arthrodesis".)

 

Figure 11: x-ray of subtalar arthrodesis (subtalar fusion). Credit: http://www.footeducation.com/foot-and-ankle-conditions/subtalar-arthritis/figure-2-subtalar-fusion/

 

Triple arthrodesis: A more dramatic option is a triple arthrodesis (Figure 12) which fuses the three joints of the hindfoot: the subtalar joint, the talonavicular joint, and the calcaneocuboid joint.

 

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Figure 12: Triple arthrodesis with fusion of the subtalar, calcaneocuboid, and talonavicular joints. A more dramatic option for treating hindfoot arthrosis compared to subtalar arthrodesis. Credit: http://www.footeducation.com/triple-arthrodesis

Treatment for OLTs

The goal of OLT treatment is to restore the surface anatomy of the talar dome and normalize reactive forces to prevent progression of arthrosis. Like osteoarthritis, OLTs can be treated non-operatively or operatively. Non-operative treatment is similar to that for osteoarthritis and involves immobilization, activity restriction, physical therapy, and use of NSAIDs. Operative treatment generally relies on ankle arthroscopy or open arthrotomy to access the OLT. Operative treatments for OLTs include:

-      Debridement and microfracture

-      Transplantation of osteochondral tissue

-      Primary repair

-      Retrograde drilling

Debridement and microfracture: This is the most common approach for treating standard size OLTstalar lesions. The unstable cartilage is arthroscopically trimmed back and then the bony base is cracked with a pick or drill ("microfractured") to stimulate subchondral bleeding and subsequent formation of a fibrin clot. The fibrin clot eventually that fills the defect and becomes undergoes transformation into fibrocartilage (type I cartilage). It is often successful (~80-85% success rate) for standard size lesions (<15mm). Patients can expect to be fully weight-bearing by 3 months after the operation.successful in about 80% of cases in which the less is less than <15mm. (If the articular surface is intact, yet there is a lesion right below it, drilling the talus from distal to proximal, up to, but not through, the articular surface (so called "retrograde drilling")  may be used. 

Transplantation of osteochondral tissue: Several transplantation techniques exist to replace the lost articular cartilage including osteochondral autograft or allograft transplantation (OATS, mosaicplasty) , and autologous chondrocyte implantation (ACI and MACI), and fresh osteochondral allografts (FOCAT). These procedures are usually reserved for OLT lesions that have failed debridement and micro fracture, and excessively large taller lesions. Osteochondral plugs for or those too large to attempt it.

During the OATS procedures (Figure 13) are , cylinders of cartilage and underlying bone that are harvested from the femoral condyle or trochlea . OATS procedures are the main means of addressing very large OLTs that have already failed debridement and microfracture. The rest of the transplantation procedures are much less common. ACI and MACI procedures deliver cultured autologous chondrocytes to the lesion via and placed within the lesion (not unlike hair plugs). . The ACI procedure comprises harvesting autologous chondrocytes, expanding them in a laboratory culture and then re-implanting this larger mass of cells into the lesion, covered by a periosteal patch or collagen matrix; however, these only address the chondral surface and are not suitable for deep lesions. FOCAT relies on an entire fresh talus to contour an allograft to the precise size and shape of the OLT. The benefit of FOCAT is that it allows surgeons to treat large lesions with underlying cysts, but the drawback is a risk of disease transmission and commonly subsidence if the graft does not incorporate fully.

 

Figure 13: OATS plug placed in medial talus. Credit: http://www.orthopaedicsone.com/display/Main/Osteochondral+lesions+of+the+ankle

 

Primary repair: Primary repair of OLTs involves fixating an osteochondral fracture fragment of the talus with screws, K-wires, or absorbable pins. It is an uncommon procedure but may be indicated in young patients with acute lesions due to significant trauma.

Retrograde drilling: This technique is based on the idea that it is possible to stimulate fibrocartilage healing to fill the defect via retrograde drilling that spares the cartilage surface. It is an uncommon procedure but may be used for cystic lesions with an intact cartilage surface.

 

  MAYBE A MORE SCHEMATIC ILLUSTRATION WOULD BE HELFUL, but I could not find one on google images....JB)

 

 

Risk factors and prevention

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