Operative Techniques in Orthopaedic Surgery (4 Volume Set) 1st Edition

455. Isolated Subtalar Arthrodesis

Aaron T. Scott and Robert S. Adelaar

DEFINITION

images Malunited calcaneal fractures pose a complex reconstructive problem.

images The presenting symptoms are caused by posttraumatic subtalar and calcaneocuboid arthritis, fibulocalcaneal impingement that displaces the peroneal tendons, talotibial impingement due to the loss of normal talar inclination, and sural nerve entrapment.

ANATOMY

images As the calcaneus is exposed to axial loading, stress occurs obliquely across the tuberosity as the tuber is lateral to the axis of the tibia (FIG 1).

images Burdeaux2 was unable to produce calcaneal fractures with the heel inverted and in the line of the tibia.

images The bone fails along this line. The tuberosity translates proximally, laterally, and anteriorly. The lateral posterior facet is driven plantarly into the calcaneus by the talus, causing a fracture at the angle of Gissane and either a tongue or joint depression pattern posteriorly. The lateral wall expands outward, further widening the heel (FIG 2).

images Calcaneal fractures have certain recurrent patterns.7,8

images There are four major fragments: the tuberosity, posterolateral facet, sustentaculum, and anterolateral fragments. The sustentacular fragment stays in anatomic position (FIG 2).

PATHOGENESIS

images When union occurs in this pathologic position, the lateral and proximal displacement of the tuberosity causes calcaneus–fibular impingement and displacement of the peroneal tendons.

images

FIG 1  Offset forces cause internal stress, which results in primary oblique fracture. (From Kitaoka H. Master Techniques of Orthopedic Surgery series: Foot and Ankle, 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 2002, with permission.)

images The disruption of the posterior facet causes posttraumatic subtalar arthritis.

images The loss of height of the heel results in the loss of the talar inclination angle and tibial talar impingement.

images Plantar subluxation of the navicular at the talonavicular joint may also occur (FIG 3).

images

FIG 2  A. Diagram of fracture demonstrating primary oblique fracture, lateral, and proximal displacement of tuberosity, impaction of posterior lateral facet, and expansion of lateral wall. B. CT scan of acute calcaneal fracture demonstrating the fracture and displacement. C. Three-dimensional volumetric reconstruction of acute fracture demonstrating the displacements. (From Kitaoka H. Master Techniques of Orthopedic Surgery series: Foot and Ankle, 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 2002, with permission.)

images

FIG 3  A. Normal anatomy and pathologic anatomy after fracture due to displacement. B. CT scan of calcaneal malunion showing posttraumatic subtalar arthritis, lateral and proximal displacement of tuberosity fracture, and lateral fibulocalcaneal impingement. C. Threedimensional volumetric reconstruction of malunion. D. Lateral view, significant malunion, reverse angle of Bohler, tibial calcaneal impingement. (B and C from Kitaoka H. Master Techniques of Orthopedic Surgery series: Foot and Ankle, 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 2002, with permission.)

NATURAL HISTORY

images The anatomic disruption, posttraumatic arthritis, and impingement cause increasing pain with activity.

images The stiff malpositioned hindfoot will lead to arthritic changes at the talonavicular joint.

images Tibial talar impingement and loss of ankle dorsiflexion puts more stress on the transverse tarsal articulation, causing secondary arthritis there.

images The displacement of the peroneal tendons and peroneal impingement will eventually cause tendinosis or tear.

PATIENT HISTORY AND PHYSICAL FINDINGS

images There will be a history of a calcaneal fracture, which may have been treated by nonoperative or operative means. Not all patients will know that they have had a heel fracture.

images Symptoms include pain at the fibulocalcaneal junction and sinus tarsi. Hypoesthesia or dysesthesia in the sphere of the sural nerve may be present.

images Physical findings are the loss of the usual step-off or indentation just distal to the tip of the fibula, loss of subtalar motion, and some loss of dorsiflexion of the ankle.

images The examiner should look for hypoesthesia in the sphere of the sural nerve with a positive percussion or Tinel test.

images Methods for examining malunited calcaneal fractures include:

images Examining for loss of “fibular sulcus.” The physician should palpate the area just distal to the tip of the fibula of both ankles. With a calcaneal malunion, there will be no sulcus for the peroneal tendons. This is indicative of the lateral displacement of the tuberosity fragment and “blow out” of the lateral wall, causing fibulocalcaneal impingement.

images Evaluating for hindfoot stiffness. The physician should examine the range of motion of the hindfoot, checking inversion and eversion. A malunion will have little if any motion, which may be painful. The stiffness is indicative of subtalar arthritis and scarring of the subtalar joint.

IMAGING AND OTHER DIAGNOSTIC STUDIES

images Radiographs show loss of the angle of Bohler, loss of talar inclination, and widening of the heel.

images The primary fracture line is often identifiable on axial heel views and Broden views.

images CT scans show all of the above and give information about the internal architecture of the heel, confirming the deformity, impingements, and arthritis.

DIFFERENTIAL DIAGNOSIS

images Posttraumatic subtalar arthritis without deformity

images Peroneal tendon tear

images Sural neuritis

images Tarsal coalition

NONOPERATIVE MANAGEMENT

images Judicious use of nonsteroidal anti-inflammatories (NSAIDs) will diminish some of the symptoms, as will sparing use of steroid injections into the sinus tarsi.

images Bracing the foot and ankle as well as the use of heel cups or heel lifts may provide some relief.

SURGICAL MANAGEMENT

images This technique is capable of correcting height losses of up to 1.5 cm. Greater height loss will require augmentation with an interpositional bone block.

images The correction-limiting factor is the amount of bone available for transverse fixation as the fragments slide relative to each other. Moving the fixation anteriorly will give windows for fixation as less translation occurs in this portion of the calcaneus.

images Indications include malunited calcaneal fractures that exhibit the signs and symptoms of fibulocalcaneoperoneal impingement, posttraumatic subtalar arthritis, loss of the angle of Bohler (and talar inclination), widening of the heel, and tibial talar impingement. Not all of these need to be present.

images Joint depression fractures are better suited for correction by this procedure than tongue-type fractures.

images If painful arthritis is present at the calcaneocuboid joint, arthrodesis of this joint may be added to the procedure.

images Smoking, diabetes, and vascular impairment must be evaluated in each patient and certainly can be contraindications to the procedure.

Preoperative Planning

images Quality radiographs are essential.

images Radiographs include weight-bearing AP, lateral, axial heel, and Broden views of the affected foot.

images A weight-bearing lateral view of the unaffected foot will provide normal parameters for the patient and allow measurement of the deformity and the amount of correction desired.

images The AP view will show the calcaneocuboid joint, which may be involved.

images The lateral view will demonstrate the loss of height and loss of talar inclination and will demonstrate tibial talar impingement.

images The axial heel film will show the oblique primary fracture line and shift of the tuberosity.

images Broden views will show the subtalar joint and demonstrate fibular calcaneal impingement.

images A CT scan of the foot with axial, semicoronal, sagittal, and three-dimensional volumetric reconstructions is suggested.

images This study will confirm what is suggested by the plain films and provide a “blueprint” of the internal architecture of the calcaneus (FIG 4).

images

FIG 4  A. AP radiograph of foot with calcaneal malunion affecting the calcaneocuboid joint. B. Lateral view of calcaneal malunion showing loss of angle of Bohler, loss of talar inclination, and anterior tibial talar impingement. C.Broden view of calcaneal malunion showing tuberosity translation, lateral impingement, and subtalar arthritis. D. Axial heel view of calcaneal malunion showing oblique primary fracture line, displacement of the tuberosity, and lateral impingement.

images

FIG 5  A. Calcaneal spreaders. B. Steinmann pin calcaneal spreaders.

images Special instruments for the procedure are required:

images 7.0-mm cannulated screws (we tend to use fully threaded screws)

images Anterior cruciate ligament drill guide to assist in placement of the guidewire for the 7.0-mm cannulated screws

images Baby Inge lamina spreaders, with and without serrations

images “Calcaneal spreaders”—wide, flat-faced, and Steinmann pin fixation spreaders (FIG 5)

images Smaller screws; 3.5-, 4.0-, or 4.5-mm cannulated screws for transverse fixation

images A “power” osteotome is helpful.

Positioning

images The patient is positioned in lateral decubitus with the affected limb up. A tourniquet is applied to the thigh. The entire leg as well as the iliac crest is prepared and draped.

Approach

images A straight incision is made from just below the tip of the fibula, directed anteriorly in the line of the fourth–fifth ray interval past the calcaneocuboid joint. (Slight posterior elongation of the incision may be needed.)

images The area at the tip of the fibula is often congested due to the impingement, and the peroneal tendons will be displaced (FIG 6).

images

FIG 6  Incision.

TECHNIQUES

OBLIQUE CALCANEAL OSTEOTOMY WITH SUBTALAR ARTHRODESIS

images Enter the subtalar joint and mobilize it.

images Place a baby Inge lamina spreader in the sinus tarsi to distract the joint. Incise the scar and capsule including the fibulocalcaneal ligament laterally.

images Incise the posterior capsule and clear tissue from the posterior calcaneus up to the flexor hallucis longus tendon, which can be observed through the joint.

images Do not incise the interosseous ligaments if possible, as these will help stabilize the sustentacular fragment to the talus (TECH FIGS 12).

images The fracture line can usually be observed on the surface of the posterior facet of the calcaneus. Mark this line (TECH FIG 3).

images Decorticate the undersurface of the talus and the posterior facet of the calcaneus. Make sure that the fracture line is preserved or marked again.

images Under fluoroscopic control, drill a Steinmann pin from superior anterior lateral to inferior posterior medial in the plane of the primary fracture.

images Visualize this on the axial heel view, which may be obtained by having the C-arm in a horizontal plane or by externally rotating the leg to verify the pin placement (TECH FIG 4).

images I perform an osteotomy in the plane of the primary fracture, using the Steinmann pin as a guide. A saw is used to start the osteotomy, which may then be finished with osteotomes. This osteotomy exits the medial wall of the calcaneus posterior and inferior to the neurovascular bundle (TECH FIG 5).

images The most difficult part of the procedure then follows. This is shifting the tuberosity medially, plantarly, and slightly posterior.

images I first distract the fragments from each other by placing the calcaneal spreader, then lamina spreaders between the fragments to relax any soft tissue attachments.

images The tuberosity may then be moved as far as possible easily, then “walked” further using small (quarterinch to half-inch) curved osteotomes to lever the tuberosity down and the medial side up (TECH FIG 6).

images Steinmann pins may be inserted transversely into the medial fragment at the superior surface of the lateral fragment to act as “dead men” (carpentry term) to prevent loss of correction. On occasion a large Steinmann pin is placed temporarily through the talus into the medial calcaneus to stabilize this fragment while the lateral tuberosity is being moved (TECH FIG 7).

images

TECH FIG 1  Peroneal tendons retracted, sinus tarsi and calcaneus exposed.

images

TECH FIG 2  Subtalar joint opened; fracture can be observed.

images

TECH FIG 3  Fracture marked and Steinmann pin placed in plane of fracture.

images

TECH FIG 4  Intraoperative radiograph confirming Steinmann pin placement.

images

TECH FIG 5  Osteotome being guided by Steinmann pin finishing osteotomy.

images It is also helpful to plantarflex the ankle to relax the triceps surae, thus facilitating the plantar shift.

images A smooth Steinmann pin may be placed across the anterior osteotomy to act as a pivot point to obtain more of a rotational correction (TECH FIG 7).

images I have had success with a Steinmann pin anchored calcaneal spreader placed from posteriorly, with one pin in the medial fragment and the second pin in the tuberosity.

images Opening this spreader aids the shift, and twisting the instrument helps oppose the fragments (TECH FIG 8).

images Once the correction has been obtained, fixation from lateral to medial is obtained using the smaller cannulated screws in compression (TECH FIGS 910).

images Use the anterior cruciate ligament drill guide to place a guide pin for the 7.0-mm cannulated screw. The entry point is the posterolateral tip of the tuberosity and the exit is through the medial aspect of the posterior facet, thus engaging fragments on both sides of the osteotomy (TECH FIGS 1112). Use the motion of the hindfoot complex to place the hindfoot in a neutral position. At this point in the procedure, the subtalar joint, talonavicular joint, and calcaneocuboid joint are mobile and height has been corrected. It is now possible to invert and evert the foot using the normal axis of motion of the hindfoot complex to a neutral position. (This is a crucial point of the procedure and differentiates it from interpositional bone block procedures where hindfoot position is dependent on the size and placement of the structural grafts.) Oppose the medial aspect of the subtalar joint to the talus and drive the guide pin into the talus. Stabilize the construct by a 7.0-mm screw in mild compression. Place a second screw if desired (TECH FIG 13).

images

TECH FIG 6  Osteotomy distracted by lamina spreaders.

images

TECH FIG 7  Steinmann pin in anterior calcaneus perpendicular to plane of osteotomy to act as pivot (this is optional), osteotomy displaced and held by Steinmann pin “dead man.”

images Check the ankle's range of motion. If a triceps surae contracture limits ankle dorsiflexion, remedy it by a percutaneous Achilles tendon lengthening.

images Harvest bone graft from the iliac crest. This may be cancellous or a corticocancellous block. Fit this graft into the empty space under the talus created by the displacement of the tuberosity with the depressed portion of the lateral posterior facet. Position this graft only to the lateral border of the talus. If a corticocancellous block is chosen, impact it into the space after properly shaping it. I have usually used cancellous bone. Allograft bone may also be used (TECH FIG 14). If a calcaneocuboid arthrodesis is needed, it is done now.

images Place a small drain if needed, and close the wounds in layers. Apply a well-padded short-leg cast. I place an AV impulse pump bladder under the cast. The cast is bivalved within 24 hours.

images

TECH FIG 8  Calcaneal distractor applied to help displace and control osteotomy fragments.

images

TECH FIG 9  Transverse fixation with two cannulated compression screws.

images

TECH FIG 10  Intraoperative radiograph, transverse screw placed, distractor in place.

images

TECH FIG 11  Anterior cruciate ligament drill guide used to place guidewire for 7.0-mm screw through tuberosity and sustentaculum.

images

TECH FIG 12  Tip of guidewire visible exiting sustentacular fragment. (From Kitaoka H. Master Techniques of Orthopedic Surgery series: Foot and Ankle, 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 2002, with permission.)

images

TECH FIG 13  7.0-mm screw being inserted. (From Kitaoka H. Master Techniques of Orthopedic Surgery series: Foot and Ankle, 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 2002, with permission.)

images

images

TECH FIG 14  A. Final construct with bone graft in place. B. Diagram of final construct, axial view. C. Diagram of final construct, oblique view. D. Radiograph, lateral view, final construct (note calcaneocuboid joint arthrodesed in this case). E. Radiograph, Broden view, final construct. (From Kitaoka H. Master Techniques of Orthopedic Surgery series: Foot and Ankle, 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 2002, with permission.)

EXTRA-ARTICULAR OBLIQUE OSTEOTOMY

images Hansen has described an extra-articular oblique osteotomy combined with subtalar arthrodesis. This is done in a similar fashion. The osteotomy does not follow the primary fracture line, but parallels it outside the joint. The obliquity of the osteotomy may be varied.

VERTICALLY ORIENTED OSTEOTOMY

images A vertically oriented osteotomy displaced directly plantarly has also been described. This increases the height of the heel and is aimed at correcting the talar inclination. This osteotomy may be shifted medially as well.

images

POSTOPERATIVE CARE

images The drains are removed on the first postoperative day. The cast and bandages are changed on the third postoperative day. The patient is non–weight-bearing in a short-leg cast for 8 to 12 weeks until union is demonstrated.

images The patient then progresses to weight bearing as tolerated. A removable fracture boot may be used.

images Physical therapy is prescribed to gain ankle range of motion and calf strengthening.

OUTCOMES

images The first cases were reported in 1993. We have continued to perform this procedure over the intervening years; about 45 procedures have been performed. The results have been reproducible. A 1.5-cm correction and increase of the Bohler angle of 25 degrees can be expected. There have been no osteotomy nonunions and one nonunion of the subtalar fusion in a smoker. There have been two patients treated by osteotomy alone (no subtalar arthrodesis) with satisfactory results.

COMPLICATIONS

images Nonunions of the osteotomy or arthrodesis sites are possible but have not proven to be a problem. Malposition of the arthrodesis is possible, but attention to inversion–eversion before fixation of the calcaneal construct to the talus avoids this potential complication.

images Inadequate correction can be avoided by proper selection of patients. The magnitude of the deformity should be within the limits of correction described above. The surgeon should have patience and be persistent in gaining correction, especially in the initial procedures undertaken. The correction is not achieved immediately, but gradually as tissues are freed and stretch.

images Wound dehiscence due to skin tension after correction has not been a problem as the wound is anterior to the greatest correction. The skin is not stretched.

REFERENCES

· Bradley SA, Davies AM. Computerized tomographic assessment of old calcaneal fractures. Br J Radiol 1990;63:926–933.

· Burdeaux BD. Reduction of calcaneal fractures by the McReynolds medial approach technique and its experimental basis. Clin Orthop Relat Res 1983;177:87–103.

· Carr JB, Hansen ST, Benirshke SK. Subtalar distraction bone block fusion for late complications of the os calcis fractures. Foot Ankle 1988;9:81–86.

· Conn HR. The treatment of fractures of the os calcis. J Bone Joint Surg 1935;17:392.

· Gallie WE. Substragalar arthrodesis in fractures of the os calcis. J Bone Joint Surg 1943;25:731–736.

· Hansen ST Jr. Calcaneal osteotomy in multiple planes for correction of major posttraumatic deformity. In: Functional Reconstruction of the Foot and Ankle, pp. 380–383. Philadelphia: Lippincott Williams & Wilkins, 2000.

· Leung K, Chan W, Shen W, et al. Operative treatment of intra articular fractures of the os calcis—the role of rigid internal fixation and primary bone grafting: preliminary results. J Trauma 1989;3:232–240.

· Palmer I. The mechanism and treatment of fracture of the calcaneus: open reduction with the use of cancellous bone grafts. J Bone Joint Surg Am 1948;30A:2–8.

· Romash MM. Reconstructive osteotomy of the calcaneus with subtalar arthrodesis for malunited calcaneal fractures. Master Techniques in Orthopedic Surgery series: The Foot and Ankle, 1st and 2nd eds. Philadelphia: Lippincott Williams & Wilkins.

· Romash MM. Reconstructive osteotomy of the calcaneus with subtalar arthrodesis for malunited calcaneal fractures. Clin Orthop Relat Res 1993;228:157–167.



If you find an error or have any questions, please email us at admin@doctorlib.info. Thank you!