Recurrent varus or valgus instability of the hindfoot (rearfoot) and ankle despite prior ligament reconstruction is a challenging problem that often requires reconstructive procedures to address underlying deformities including cavus foot and pes planovalgus, respectively. Procedure selection will be the main focus of this chapter, intended to help the surgeon decide which combination of forefoot, rearfoot, and ankle procedures are best able to address these complex biomechanical deformities, which often involve failure of the soft tissue structures and late-stage degenerative joint disease (DJD). Evidence is lacking to help guide surgical treatment as revision surgery is difficult to study since each patient presents with a unique set of circumstances regarding underlying deformity, degree of tissue or joint degeneration, and past surgical treatment.
Lateral Ligament Insufficiency of the Hindfoot and Ankle
Chronic lateral ankle instability occurs in approximately 20% of patients who have acute ankle sprains, which largely represents the population that is treated with lateral ankle stabilization (LAS) procedures.1,2 A small subset of those who undergo surgical repair have persistent or recurrent pain and instability, which can be associated with underlying cavus foot deformity, resulting in failure of the repaired lateral collateral ligaments. Revision surgery under these circumstances will often require some degree of cavus foot reconstruction including osseous procedures and tendon balancing in addition to repeat lateral collateral ligament repair.
Patients who have recurrent chronic ankle instability (CAI) symptoms despite prior surgical intervention also frequently have other concomitant pathologies: synovial impingement of the ankle and/or subtalar joint (STJ), osteochondral lesions (OCD), DJD, and peroneal tendinopathy, which need to be addressed with revision surgery (Figure 18.1).3
History and Physical Examination for Recurrent Lateral Ankle Instability
Preoperative workup should focus on identifying related intra-articular and extra-articular pathologies. Prior medical records should be reviewed regarding the original procedure, intraoperative findings, and postoperative rehabilitation protocol, which may provide insight into why the original procedure failed. The surgeon should identify if the patient did well after the original procedure and then had another traumatic ankle injury. This scenario is quite different from the that of the patient who never fully recovered after the prior LAS surgery. Physical examination should include range of motion of the ankle, subtalar, and midtarsal joints; gait assessment; and determination of weight-bearing alignment of the foot and ankle. Ligamentous laxity should be assessed by history and examination. Location of maximal tenderness on examination is very telling, especially to evaluate for pain on palpation of the peroneal tendons or of the sinus tarsi indicating STJ involvement.
Imaging Considerations and Stress Imaging Pearls
The authors’ routine radiographic protocol includes a 5-views weight-bearing foot and ankle series. This includes anterior-posterior and mortise ankle views plus 3 views of the foot. The lateral view in this series should fully image both the foot and ankle. Periankle accessory ossicles or an anterior tibial spur may be added sources of chronic pain in patients with ankle instability and should be evaluated on standard foot and ankle views. A long leg axial (LLA) view should be considered to better assess frontal plane alignment of the heel. The authors’ LLA imaging protocol has been previously published, which is beneficial to avoid inconsistent patient positioning, which can be misleading regarding true tibia to calcaneus alignment.4 True frontal plane tibia to calcaneus alignment is captured with both feet in angle and base of gait while standing with the foot at 90° to the leg. The central beam is at 45° to the floor with overlap of the tibia through the second metatarsal. Intraoperative LLA imaging can also capture the tibia through second metatarsal alignment for consistent imaging at all stages of care (Figure 18.2).
Magnetic resonance imaging (MRI) is of limited benefit regarding the function of the lateral collateral ligaments in patients with recurrent sprains and prior surgical repair due to extensive scarring of the ligaments. MRI in this population is very helpful to assess for peroneal tendon pathology and OCDs but does not typically show synovial impingement in the ankle or STJ. These issues are best identified by history, clinical examination, and diagnostic injection. Computed tomography (CT) may be used to further evaluate degenerative arthritis, tarsal coalitions, and subchondral cystic changes that are picked up on plain radiographs and MRI (Figure 18.4).
Is Generalized Ligamentous Laxity Present and Does This Change the Treatment?
Surgical treatment in the presence of generalized ligamentous laxity should focus on STJ arthrodesis where appropriate as an adjunctive procedure to correct cavus deformity. Native tissues should be supported with synthetic materials or at least cadaver tendon allografts when performing LAS.
Revision Lateral Ankle Stabilization
Revision surgery for lateral collateral ligament insufficiency typically involves anatomic repair along with augmentation procedures. Synthetic reinforcement provides increased mechanical resistance of the anatomical repair and enables early rehabilitation. A modified Brostrom procedure augmented with suture tape and bone anchors is an example of this. Tenodesis procedures using autograft or allograft for reconstruction can be completed using various tendons: Storen described using the Achilles; Niethard and Anderson described augmentation using the plantaris.6
Is Ankle Arthroscopy a Routine Component of Revision Lateral Ankle Stabilization?
Arthroscopic inspection and debridement of the ankle joint at the time of LAS may improve detection of impingement lesions and concomitant OCDs, which are common in patients with CAI. The open incision for LAS may not afford access or appropriate viewing of these lesions, and pathology can be missed when the surgeon peaks into the joint through the open LAS incision. Surgical pearls include using a modified nerve-centric incisional approach when performing combined LAS and arthroscopy of the ankle and STJ (Figure 18.5).
Arthroscopic lateral ligament repair with suture tape has similar sustained clinical outcomes compared with arthroscopic Brostrom-type reconstruction, but research is lacking when performing revision surgery.7 The arthroscopic approach may not make sense when revision surgery involves open reconstruction for deformity correction. Meticulous dissection is also necessary to avoid the sural and superficial peroneal nerves and peroneal tendons.8
Who Needs a Lateralizing Calcaneal Osteotomy?
Ongoing instability following primary lateral ligament repair is common in patients with cavus deformity with or without underlying neurologic disorder. Hindfoot varus malalignment and related forefoot deformity is prevalent in patients with ankle instability, and the surgeon should consider more complex reconstructions including osteotomies or arthrodesis when performing revision lateral ankle ligamentous repairs. Failure to correct hindfoot varus accounts for the most common reason for failure in isolated ligament reconstruction.9 For patients with fixed hindfoot deformity, or those with residual varus after midfoot surgery, a calcaneal osteotomy is indicated.
Does the Patient Need Major Cavus Foot Reconstruction?
Cavus and cavovarus deformity including forefoot valgus and heel varus should be assessed prior to formulating a revision surgery plan since underlying foot deformity can be a primary cause of failed prior surgery and heel osteotomy alone may be insufficient. The Coleman “block test” can be used to determine whether hindfoot varus is reducible or not and to determine the impact of forefoot valgus on rearfoot alignment. The peroneal tendons should be palpated and assessed for pain, swelling, weakness, subluxation, or other instability. Metatarsus adductus, hammertoe deformity, and a heightened medial longitudinal arch are common. Ankle joint range of motion should include the Silverskiold test to determine if gastrocnemius and/or soleal equinus is present; outcomes will determine if a gastrocnemius recession or tendo-Achilles lengthening procedure is warranted.
Assessment for supramalleolar deformity is important since varus malalignment of the tibial plafond may be treated with opening-wedge supramalleolar tibial osteotomies with fibular osteotomies with or without calcaneal osteotomy, midfoot osteotomy, or arthrodesis. In these cases, the lateral ankle ligament reconstruction may not be necessary. Failures in supramalleolar osteotomies may involve osseous undercorrection of the fibular deformity, ligamentous insufficiency, and significant intra-articular arthritis. All aspects of the cavovarus deformity need to be corrected to avoid chronic instability and continuous pain and deformity.11
Considerations of First Metatarsal Dorsiflexory Wedge Osteotomy Versus Midfoot Arthrodesis
How to Identify and Treat Subtalar Joint Pain and Instability
It is important to evaluate the STJ in patients with CAI through direct palpation of the sinus tarsi and assessing range of motion to determine if STJ involvement might be a source of pain or instability. Despite prior ankle ligament repair, the patient may describe CAI symptoms due to chronic impingement or instability of the STJ. Failure to recognize this may lead to failure to relieve pain with revision surgery. Local anesthetic injection into the sinus tarsi can be a useful therapeutic and diagnostic test to localize pain and to assess if a subtalar arthroscopy or arthrodesis would be appropriate. Cervical ligament tears and interosseous talocalcaneal ligament tears can be assessed best on arthroscopy but may also be identified on MRI. Arthroscopic debridement of the sinus tarsi is a useful adjunctive procedure to LAS, and patients with pain on palpation of the sinus tarsi that resolves with diagnostic sinus tarsi injection should be considered for arthroscopic debridement.