Shape memory staples have several uses in both hand and foot and ankle surgery. There is relatively little data available regarding the biomechanical properties of staples, in terms of both the compression achieved and potential decay of mechanical advantage with time. An understanding of these properties is therefore important for the surgeon.

Two blocks of synthetic polyurethane mimicking properties of cancellous bone were fixed in jigs to both the actuator and 6 degree-of-freedom load cell of an MTS servohydraulic testing machine. With the displacement between the blocks held constant the peak value and subsequent decay in compressive force applied by both the smooth and barbed version of the nitinol OSStaple (Biomedical Enterprises), Easyclip (LMT), Herbert Bone Screws (Martin) and the Headless Compression Screw (Synthes) was measured. Nitinol staples were energised once only. A second experiment was conducted to assess the effects of repeated energisation on these parameters.

The Easyclip staples achieved a mean peak force of 5.2N, whilst the smooth and barbed OSStaples achieved values of 9.3N and 5.7N, respectively. The Herbert screws achieved a mean peak force of 9N and the headless compression screws 23.9N. The mean peak force achieved with 2 Easyclip staples in parallel was 8.1N. Following the application of a single energisation the OSStaples exhibited a significant reduction in compressive load, losing up to approximately 70% of the peak value attained. The repeated energisation of these nitinol staples produced progressive increases in both peak and trough loads, the positive effects exhibited a plateau with time.

Performance of both OSStaples was comparable to the Herbert screw with regard to reduction load applied across a simulated fracture plane. The maximum load applied by the OSStaples diminished with time. Staples provide fixation without violating the fracture plane which has the potential to offer some benefits from a healing perspective.

Introduction: Lesser toe problems and metatarsalgia are common complaints in patients presenting with foot problems. Associated toe deformities include mallet toes, hammer toes, claw toes. The patient may complain of pain over the proximal interphalangeal joint from shoe ware, diffuse or localized pain under the metatarsal heads, or swelling and irritation of the metatarsophalangeal joint. Most patients can be treated with shoe ware modification, NSAID medication, tapping of toes, orthotics, or steroid injections. Surgical treatment includes flexor to extensor transfers, PIP excision arthroplasty, plantar condylectomy and metatarsal osteotomy.

Indications and Complications: The osteotomy is performed when there instability of the MTP joint, reduction of MTP joint subluxation or dislocation, relatively long ray with transfer metatarsalgia. Complications include avascular necrosis, joint stiffness, transfer metatarsalgia to subsequent toes, and plantar flexion of the metatarsal.

Surgical Technique: The Weil osteotomy is performed through a dorsal incision, performing a dorsal capsulotomy of the MTP joint and plantar flexing the proximal phalanx to expose the metatarsal head. The osteotomy is started in dorsal aspect of the metatarsal head and is made along the shaft keeping parallel to the floor. Key points are to make a long osteotomy cut to allow broad surface area for healing, avoid lowering the head by performing the cut parallel to the floor. The head will naturally displace proximally, most authors recommending 5–10mm of shortening.

Fixation: The osteotomy is fixed using a twist off screw. Factors that influence fixation include angle of screw insertion, size of the screw and the number of screws. Fixation in relatively porotic bone is improved when using two screws.