Introduction

Sliding calcaneus osteotomy may be indicated to correct alignment of the ankle joint with the aim to diminish symptoms and prevent progression of degenerative changes. The ankle joint has a high congruency. A decrease in joint congruence will increase contact pressure per area. Clinical and basic scientific investigations have shown that loading and joint motion can influence the healing of articular cartilage. Malalignment will result in an asymmetric increase of contact pressure. Biomechanical experiments have demonstrated that in varus and supination the maximum pressure is located on the medial border of the talus, while in valgus and pronation the maximum pressure is located on the lateral talar border. It is therefore important to correct malalignment in patients with asymmetric degenerative changes in the ankle.

Sliding calcaneus osteotomy is an established procedure for treatment of an acquired adult flatfoot, to correct hindfoot valgus in case of deltoid ligament insufficiency, cavovarus foot deformity, osteochondral defects, and treatment of unicompartimental osteoarthritis.  

Anatomy

The calcaneus is the largest bone in the foot and forms the subtalar joint with the talus and with the cuboid, the calcanealcuboid articulation. On the posterior superior facet the Achilles tendon is inserted and on the medial side of the bone the sustentaculum tali is located. The sustentaculum serves as attachment of calcaneo-navicular, tibiocalcaneal and medial talocalcaneal ligament and as groove for the flexor hallucis longus tendon. On the lateral side the peroneal trochlea can be distinguished (groove for the peroneus longus tendon). The calcaneus further serves as insertion point for the gastrocnemius, soleus and plantaris muscles. They have a variety in function, including plantar flexion of the foot, flexion of the knee, aids in walking, running, jumping, and steadies the leg on the ankle during standing.
History & Physical examination
Malalignment of the ankle can lead to asymmetric degenerative changes. An OCD in a malaligned ankle can remain symptomatic in spite of adequate initial treatment due to high asymmetric loading.  Degenerative changes in the ankle can cause stiffness, diminished range of motion and pain. OCDs typically cause deep pain during and after weight bearing. Sometimes there is recurrent swelling, synovitis, and sometimes locking complaints.
It is important to assess the amount of malalignment of the ankle by means of physical examination. This is assessed by measuring the calcaneocrural angle of the patient in standing position. (Stiehl, J.B., Inman's joints of the ankle, 1999)

History & Physical examination

Malalignment of the ankle can lead to asymmetric degenerative changes. An OCD in a malaligned ankle can remain symptomatic in spite of adequate initial treatment due to high asymmetric loading.  Degenerative changes in the ankle can cause stiffness, diminished range of motion and pain. OCDs typically cause deep pain during and after weight bearing. Sometimes there is recurrent swelling, synovitis, and sometimes locking complaints.

It is important to assess the amount of malalignment of the ankle by means of physical examination. This is assessed by measuring the calcaneocrural angle of the patient in standing position. (Stiehl, J.B., Inman's joints of the ankle, 1999)

Diagnostic Imaging

Conventional radiographs of the ankle consist of weight bearing anteroposterior (mortise) and lateral views of both ankles. A long axial or hindfoot alignment view to establish the amount of malalignment can be obtained in order.

Surgical treatment

Planning

Before starting, mark your side. Thirty minutes before incision 1500 mg of Cefuroxim i.v. is administered. Antithrombotics (fondaparinux, 2.5 mg subcutaneously) is started 6 hours postoperative until the day the plaster cast is removed and weight bearing is allowed.

Rehabilitation

The incision is sutured. Postoperative an X-ray is made. Aftercare consists of a non weight bearing short-leg plaster cast for 4 weeks. After 10-14 days the stitches are removed and after 4 weeks a weight bearing cast is applied for another 4 weeks. After these 8 weeks, radiographs are obtained to confirm consolidation of the osteotomy. If consolidation is present, the cast is removed and full weight bearing is allowed.

Check ups:

• 10-14 days: wound inspection and removal of stitches
• 8 weeks: wound inspection and X-rays to confirm consolidation of osteotomy
• 6 months: check ROM, weight bearing X-ray
• 1 year: check ROM, weight bearing X-ray. In case of discomfort of plate, removal can be scheduled.

Recommended literature

Dwyer FC. Osteotomy of the calcaneum for pes cavus. J. Bone Joint Surg. Br., 1959 Jan;41B(1):80-86.
Hintermann B. Medial ankle instability. Foot Ankle Clin. 2003;8(4):723-738.

Johnson KA, Strom DE. Tibialis posterior tendon dysfunction. Clin. Orthop. Relat. Res. 1989;239:196-206.

Pagenstert GI, Hintermann B, Barg A, Leumann A, Valderrabano V. Realignment surgery as alternative treatment of varus and valgus ankle osteoarhritis. Clin. Orthop. Relat. Res. 2007;462:156-168.

Reilingh ML, Beimers L, Tuijthof GJ, Stufkens SA, Maas M, van Dijk CN. Measuring hindfoot alignment radiographically: the long axial view is more reliable than the hindfoot alignment view. Skeletal Radiol. 2010;39(11):1103-1108.