Michael P. Clare and Roy W. Sanders
DEFINITION
A calcaneal malunion refers to residual bony malalignment and associated clinical sequelae resulting from inadequate treatment of a displaced intra-articular calcaneal fracture.
ANATOMY
The calcaneus is an odd-shaped bone that supports full body weight and provides a lever arm through which the powerful gastrocnemius–soleus complex assists with forward propulsion during gait (FIG 1).
The calcaneus also provides articulations for the subtalar and calcaneocuboid joints, and thus is integral to function of the triple joint complex of the hindfoot for normal ambulation and accommodation to uneven ground (FIG 2).
The normal orientation of the calcaneus is reflected radiographically as calcaneal pitch, talocalcaneal height, and calcaneal length, which directly affect the three-dimensional alignment of the hindfoot and midfoot and indirectly affect ankle dorsiflexion (FIG 3).
PATHOGENESIS
In a displaced intra-articular calcaneal fracture, there is typically not only intra-articular displacement of the posterior facet but also loss of calcaneal height, shortening and varus angulation of the calcaneal tuberosity, extension into the anterior process or calcaneocuboid joint, and expansion of the lateral calcaneal wall.
Nonoperative treatment, or inadequate operative treatment, of a displaced intra-articular calcaneal fracture results in a calcaneal malunion, which affects function of the ankle, subtalar, and calcaneocuboid joints and leads to pain and disability.4,15
Associated sequelae include:
Posttraumatic subtalar and calcaneocuboid arthritis due to residual articular incongruity8,17
Lateral subfibular impingement from residual lateral wall expansion and heel widening8,16
FIG 1 • The calcaneus serves as a lever arm for the powerful gastrocnemius–soleus complex.
Peroneal tendon stenosis, tenosynovitis, or subluxation–dislocation as a result of adjacent bony prominence2,5,12
Anterior ankle impingement and loss of ankle dorsiflexion due to loss of calcaneal height, resulting in relative dorsiflexion of talus3
Hindfoot malalignment (typically varus) affecting gait pattern and shoe wear and potentially producing a leglength discrepancy13
NATURAL HISTORY
Patients with displaced intra-articular calcaneal fractures that go on to malunion typically have a poor result, including pain with weight bearing, limitations in shoe wear, secondary gait alterations, and progressive posttraumatic subtalar arthritis.6,11
PATIENT HISTORY AND PHYSICAL FINDINGS
History of prior calcaneal fracture (displaced intra-articular fracture) (the examiner should note the prior method of treatment, operative or nonoperative)
Pain with weight bearing (standing or walking, particularly on uneven terrain)
Thorough examination of the ankle and hindfoot should also include assessment of:
Skin and soft tissue envelope, including location of previous surgical incisions, overall mobility of lateral hindfoot skin, swelling, or any dystrophic changes where present
Neurovascular status (particularly the presence or absence of palpable pulses)
Hindfoot malalignment: excessive hindfoot varus or valgus relative to uninvolved limb represents malalignment
Subtalar range of motion: decreased subtalar range of motion may result from posttraumatic arthritis
Subtalar arthritis: tenderness to palpation suggests articular degeneration
Subfibular impingement, bony prominence, and tenderness suggest peroneal stenosis or tenosynovitis from residual lateral wall expansion. Peroneal tendons may actually be subluxed or dislocated in severe cases.
FIG 2 • Normal weight-bearing lateral radiograph demonstrating posterior and middle facets of subtalar joint (black arrows), and calcaneocuboid joint (white arrows).
FIG 3 • Normal weight-bearing lateral radiograph; note downward orientation of talus. A. Calcaneal pitch angle. B. Talocalcaneal height. C. Talo–first metatarsal angle.
Ankle range of motion: decreased dorsiflexion compared to uninvolved limb may indicate anterior impingement from relative dorsiflexion of talus and loss of calcaneal height.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Standard weight-bearing radiographs of the ankle and foot, in addition to a Harris axial view of the calcaneus, reveal the calcaneal malunion.
The lateral view of the hindfoot demonstrates loss of calcaneal height and relative dorsiflexion of the talus (FIG 4).
The mortise view of the ankle demonstrates residual lateral wall expansion and degenerative changes in the subtalar joint, as well as a fracture-dislocation variant fragment where present (FIGS 5 AND 6).
The axial view shows residual shortening of the calcaneus, and any hindfoot malalignment where present (FIG 7).
Once the diagnosis is established, a CT scan of the calcaneus, including axial, sagittal, and 30-degree semicoronal images, further delineates the extent of subtalar and calcaneocuboid arthritic change, hindfoot malalignment, lateral wall exostosis, and subfibular impingement, as well as any associated talar or other ankle joint pathology (FIGS 8–10).
DIFFERENTIAL DIAGNOSIS
Posttraumatic subtalar arthritis (without malunion)
Subtalar osteoarthritis
FIG 4 • Weight-bearing lateral radiograph of calcaneal malunion. Note loss of calcaneal height (black arrows), producing relative dorsiflexion of talus and anterior impingement at ankle joint (white arrow).
FIG 5 • Weight-bearing mortise radiograph of calcaneal malunion; note residual intra-articular step-off and associated degenerative changes (black arrows).
Calcaneal fracture nonunion
Lateral ankle instability or peroneal tendon pathology
NONOPERATIVE MANAGEMENT
Nonoperative treatment options are limited but consist primarily of supportive modalities to lessen inflammation and painful motion through the hindfoot.
A lace-up ankle brace, UCBL, ankle–foot orthosis, or Arizona-type brace may be beneficial in limiting painful subtalar motion and providing symptomatic relief. A prefabricated fracture boot may be used intermittently for episodes of arthritic flare-up.
FIG 6 • Weight-bearing mortise radiograph of calcaneal malunion from fracture-dislocation variant pattern. Note residually dislocated posterolateral fragment wedged within talofibular joint (black arrows), and subtle varus tilt within ankle mortise (white arrow), suggesting incompetence of lateral ligamentous complex.
FIG 7 • Axial radiograph of calcaneal malunion. Note marked residual shortening (black arrows) and varus angulation of calcaneal tuberosity (dashed lines).
Intermittent use of nonsteroidal anti-inflammatory medication can also be beneficial in disrupting the inflammatory cycle.
Activity modification, such limited standing and walking, particularly on uneven terrain, may also lessen symptoms.
SURGICAL MANAGEMENT
We use the Stephens-Sanders classification system and treatment protocol for calcaneal malunions, which is based on CT evaluation.17 Type I malunions include a large lateral wall exostosis, with or without far lateral subtalar arthrosis. Type II malunions include a lateral wall exostosis and subtalar arthrosis involving the entire width of the joint. Type III malunions include a lateral wall exostosis, subtalar arthrosis, and malalignment of the calcaneal body resulting in significant hindfoot varus or valgus angulation (FIG 11).
FIG 8 • Semicoronal CT image demonstrating subfibular impingement (white arrow) and posttraumatic arthritic changes in posterior facet (black arrows).
FIG 9 • Sagittal CT image demonstrating loss of calcaneal height (black arrows).
Preoperative Planning
The calcaneal malunion is evaluated with plain radiographs and CT scan and classified according to the Stephens-Sanders classification.17 Treatment is based strictly on malunion type:
Type I malunions are managed with a lateral wall exostectomy and a peroneal tenolysis.2,5,12
Type II malunions are managed with a lateral wall exostectomy, peroneal tenolysis, and a subtalar bone block arthrodesis, using the excised lateral wall as autograft.10
Type III malunions are managed with a lateral wall exostectomy, peroneal tenolysis, subtalar bone block arthrodesis, and a calcaneal osteotomy to correct hindfoot malalignment.7
The procedure requires use of a radiolucent table and a standard C-arm.
FIG 10 • Semicoronal CT image of calcaneal malunion from fracture-dislocation variant pattern (black arrows). This 25-year-old laborer had unfortunately been treated nonoperatively and rapidly developed posttraumatic arthritis.
FIG 11 • Stephens-Sanders classification of calcaneal malunions. A. Type I malunion. B. Type II malunion. C. Type III malunion.
A pneumatic thigh tourniquet is used. The procedure should be completed within 120 to 130 minutes of tourniquet time to minimize potential wound complications.
Positioning
The patient is placed in the lateral decubitus position on a beanbag. The lower extremities are positioned in a scissor configuration such that the operative (“up”) limb is flexed at the knee and angles toward the distal, posterior corner of the operating table, while the nonoperative (“down”) limb is extended at the knee and lies away from the eventual surgical field. This facilitates intraoperative fluoroscopy without interference from the nonoperative limb. Padding is placed beneath the contralateral limb to protect the peroneal nerve, and an operating “platform” is created with blankets and foam padding to elevate the operative limb (FIG 12).
Alternatively, the prone position may be used for bilateral procedures.
FIG 12 • Lateral decubitus position. Note scissor configuration of limbs to facilitate intraoperative fluoroscopy.
Approach
We use the extensile lateral approach for surgical management of the calcaneal malunion, regardless of malunion type. The lateral calcaneal artery, typically a branch of the peroneal artery, supplies the majority of the full-thickness flap.1 Thus, strict attention to detail with respect to placement of the incision and gentle handling of the soft tissues is of paramount importance.
The planned extensile lateral approach is then outlined on the skin:
The incision begins about 2 cm proximal to the tip of the lateral malleolus, just lateral to the Achilles tendon and thus posterior to the sural nerve and the lateral calcaneal artery, and the vertical limb extends toward the plantar foot.
The horizontal limb is drawn along the junction of the skin of the lateral foot and heel pad; this skin demarcation can be identified by compressing the heel. We substitute a gentle curve where these two lines combine to form a right angle, primarily to avoid apical necrosis. The horizontal limb also includes a gentle anterior curve along the skin creases distally, ideally ending over the calcaneocuboid articulation (FIG 13).
FIG 13 • Planned incision for extensile lateral approach.
TECHNIQUES
EXTENSILE LATERAL APPROACH
Place the limb on a sterile bolster and begin the incision at the proximal portion of the vertical limb. It becomes full thickness at the level of the calcaneal tuberosity—literally “straight to bone,” while avoiding any beveling of the skin.9 Again lessen scalpel pressure beyond the apical curve of the incision, and develop a layered incision along the horizontal limb of the incision.
Raise a full-thickness, subperiosteal flap starting at the apex, specifically avoiding use of retractors until a considerable subperiosteal flap is developed, in order to prevent separation of the skin from the underlying subcutaneous tissue (TECH FIG 1A).
Sharply release the calcaneofibular ligament from the lateral wall of the calcaneus, and release the adjacent peroneal tendons from the peroneal tubercle through the cartilaginous “pulley” to avoid iatrogenic injury (TECH FIG 1B).
Use a periosteal elevator to gently mobilize the tendons along the distal portion of the incision, which then exposes the anterolateral calcaneus. Thus, the peroneal tendons and sural nerve are contained entirely within the flap, and devascularization of the lateral skin is minimized (TECH FIG 1C).
Continue deep dissection to the sinus tarsi and anterior process region anteriorly, the calcaneocuboid joint distally, and the superior-most portion of the calcaneal tuberosity posteriorly.
Place three 1.6-mm Kirschner wires for retraction of the subperiosteal flap: one into the fibula as the peroneal tendons are slightly subluxed anterior to the lateral malleolus; a second in the talar neck; and a third in the cuboid as the peroneal tendons are levered away from the anterolateral calcaneus with a periosteal elevator. Thus, each Kirschner wire retracts its respective portions of the peroneal tendons and full-thickness skin flap (TECH FIG 1D).
TECH FIG 1 • Extensile lateral approach. A. Note absence of retractors until a sizeable subperiosteal flap has been raised. B. Mobilization of peroneal tendons (white arrows). C. Gentle mobilization of flap along anterolateral wall of calcaneus. D. 1.6-mm Kirschner wire retractors.
LATERAL WALL EXOSTECTOMY
A lateral wall exostectomy is completed for all three malunion types.
Starting posteriorly, angle the A/O osteotomy saw blade slightly medially relative to the longitudinal axis of the calcaneus, preserving more bone plantarly and thereby providing decompression of the subfibular impingement (TECH FIG 2A,B).
Take care throughout the exostectomy to avoid violation of the talofibular joint: place a small Bennett-type retractor at the level of the posterior facet (TECH FIG 2B).
Continue the exostectomy to the level of the calcaneocuboid joint and complete it with an osteotome. Remove the fragment en bloc as a single fragment and preserve it in saline on the back table for later use as autograft (TECH FIG 2C).
The width of the exostectomy fragment varies (about 10 to 15 mm) but is generally proportional to the extent of loss of calcaneal height and lateral wall expansion from the original injury, which reflects the amount of initial energy involved.
TECH FIG 2 • Lateral wall exostectomy. A. Intraoperative photo demonstrating vertical axis of limb (line A) and plane of lateral wall exostectomy (line B). B. Use of A/O osteotomy saw; note presence of small Bennett retractor protecting talofibular joint. C. Exostectomy fragment is removed en bloc for later use as autograft.
SUBTALAR BONE BLOCK ARTHRODESIS
In patients with a type II or III malunion, gently mobilize the subtalar joint with a small osteotome, carefully identifying the plane of the posterior facet.
Place a laminar spreader and meticulously débride the joint of any residual articular surface while preserving the underlying subchondral bone; we prefer to use a sharp periosteal elevator and pituitary rongeur.
Irrigate the joint and make multiple perforations in the subchondral surface with a 2.5-mm drill bit to stimulate vascular ingrowth. Place highly concentrated platelet aspirate both within the joint and upon the previously resected lateral wall fragment.
Place the lateral wall fragment within the subtalar joint as an autograft bone block; we prefer to place the laminar spreader posteriorly to facilitate bone block placement (TECH FIG 3A).
Position the fragment such that the widest portion of the autograft is oriented posteromedially to avoid varus malalignment (TECH FIG 3B).
Fill any remaining voids within the subtalar joint with supplemental allograft.
With the subtalar joint held in neutral to slight valgus alignment, obtain definitive stabilization with two large (6.5 to 8.0 mm) partially threaded cannulated screws placed from posterior to anterior in diverging fashion: the more lateral screw is placed in the talar dome, while the more medial screw is placed in the talar neck.
A third screw may be placed extending from the anterior process region into the talar neck and head, avoiding violation of the talonavicular articulation (TECH FIG 4).
TECH FIG 3 • Placement of autograft bone block. A. Note position of laminar spreader within subtalar joint posteriorly. B. Postoperative semicoronal CT image demonstrating proper orientation of autograft bone block (black triangle), with widest portion placed posteromedially.
TECH FIG 4 • Definitive stabilization. A. Intraoperative fluoroscopic lateral view demonstrating diverging orientation of large cannulated screws posteriorly, and supplemental screw traversing middle facet. B. Intraoperative fluoroscopic mortise view; note slight medial angulation to avoid violation of talofibular joint. C. Intraoperative fluoroscopic anteroposterior view; note transverse orientation of anterior screw, avoiding violation of talonavicular joint (black arrows). D. Intraoperative fluoroscopic axial view; note neutral hindfoot alignment.
CALCANEAL OSTEOTOMY
For patients with a type III malunion, angular malalignment in the calcaneal tuberosity is corrected before implant placement.
A Dwyer-type closing wedge osteotomy is performed for those with varus malalignment (TECH FIG 5).
A medial displacement calcaneal osteotomy is used for those with valgus malalignment (rare).
Because the plane of the osteotomy is nearly parallel to the plane of the posterior facet, the osteotomy and subtalar joint are stabilized simultaneously as described above.
TECH FIG 5 • Calcaneal osteotomy. Dwyer closing wedge osteotomy for correction of varus malalignment in calcaneal tuberosity.
PERONEAL TENOLYSIS
Remove the Kirschner wire retractors and incise the peroneal tendon sheath along the undersurface of the subperiosteal flap over a length of 2 to 3 cm. A peroneal tenolysis is then completed.
Advance a Freer elevator within the tendon sheath to the level of the lateral malleolus proximally, thereby mobilizing the peroneal tendons.
Assess the competence of the superior peroneal retinaculum (SPR) by gently levering the Freer elevator forward while observing the overlying skin. The presence of an endpoint indicates an intact retinaculum, but with an incompetent SPR the elevator will easily slide anterior to the lateral malleolus, with no demonstrable endpoint.
Advance the Freer elevator within the tendon sheath distally to the cuboid tunnel.
SUPERIOR PERONEAL RETINACULUM REPAIR
If the SPR is incompetent, make a separate 3-cm incision along the posterior border of the lateral malleolus, exposing the tendon sheath.
With the peroneal tendons held reduced in the peroneal groove, use one or two suture anchors to secure the detached SPR to bone (TECH FIG 6).
Reassess tendon stability using a Freer elevator in the same manner.
TECH FIG 6 • Superior peroneal retinaculum repair and suture imbrication of incompetent superior peroneal retinaculum.
CLOSURE
Place a deep drain exiting proximally in line with the vertical limb of the incision.
Place deep no. 0 absorbable sutures in interrupted, figure 8 fashion, beginning with the apex of the incision and progressing to the proximal and distal ends. The sutures are temporarily clamped until all sutures have been passed, then hand-tied sequentially, starting at the proximal and distal ends, and working toward the apex of the incision, so as to eliminate tension at the apex of the wound (TECH FIG 7A).
Because of the lateral decompression from the exostectomy, the flap should close fairly easily with minimal tension (despite restoration of calcaneal height).
Close the skin layer with 3-0 monofilament suture using the modified Allgöwer-Donati technique, again starting at the ends and working toward the apex (TECH FIG 7B).
Deflate the tourniquet and place sterile dressings, followed by a bulky Jones dressing and Weber splint.
TECH FIG 7 • Flap closure. A. Deep absorbable sutures placed and temporarily clamped. B. Skin closure using modified Allgöwer-Donati technique.
POSTOPERATIVE CARE
For type I malunions, the patient is converted to a prefabricated fracture boot at 2 weeks postoperatively. Weight bearing and range-of-motion exercises are initiated once the incision has fully healed.
For type II or type III malunions, the patient is converted to a short-leg non–weight-bearing cast at 2 to 3 weeks and again at 6 to 7 weeks postoperatively. Weight bearing is not permitted until 10 to 12 weeks postoperatively, at which point radiographic union is confirmed.
The patient is then converted to a prefabricated fracture boot, and weight bearing is initiated. The patient is gradually transitioned to regular shoe wear and activity is advanced as tolerated thereafter.
OUTCOMES
This is intended as a salvage procedure for pain relief and restoration of alignment.
We recently reported our intermediateto long-term results of this protocol4:
The initial arthrodesis union rate was 93%.
Ninety-three percent had neutral or slight valgus hindfoot alignment; 100% had plantigrade foot.
There was no statistical difference in outcome scores among the three malunion types.
Significantly greater restoration of talocalcaneal height was found among patients with type III malunions.
COMPLICATIONS
Delayed wound healing, wound dehiscence, deep infection
Arthrodesis delayed union or nonunion
Postoperative ankle stiffness
(Late) Lateral ankle (“sprain”) pain from coronal plane stresses applied to ankle joint
(Late) Compensatory ankle joint arthritis (theoretical)
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