Impingement-related osteolysis in Motec total wrist arthroplasty: an explant analysis and review of the literature.

We present five cases of osteolysis in the Motec total wrist prosthesis, three around the radial implant, one around the metacarpal implant and one around both. Three of these were progressive and required revision, and biomechanical explant analyses of these revised prostheses were performed. Ex vivo testing of the contact points of the Motec implants was also performed at maximum extension. Here, impingement occurs between the metacarpal screw and the dorsal rim of the cup (non-articulating surfaces) with the short-necked prosthesis, leading to metacarpal screw damage, titanium debris formation and osteolysis. An analysis of three previously published cases suggests that this may have been the likely mode of failure in those cases. This complication is preventable by avoiding use of the short-neck prosthesis.Level of evidence: IV.

Modes of failure following locking plate fixation of the distal radius: a thematic analysis of 517 fractures.

Anterior locking plate fixation of the distal radius is a common procedure with reliable results. Failure of fixation is sometimes seen. The aim of the present study was to identify the reasons for failure. In total, 517 cases met the study inclusion criteria. Of them, 23 cases had failure of fixation (4.4%). Failure analysis generated qualitative data. Subsequent thematic analysis identified the primary mode of failure and contributing factors. Primary modes were identified as failure to support all key fracture fragments (n = 20), wrong choice of implant (n = 1), failure of union (n = 1) and poor bone quality (n = 1). Contributing factors were errors in plate positioning, fracture reduction, implant selection and screw configuration, as well as fracture pattern complexity and poor bone quality. Most failed fixations had a primary mode and two or three contributing factors. Overall anterior plating is reliable with a low rate of surgical failure. Knowledge of failure modes will aid operative planning and prevent failure.Level of evidence: V.

Irreducible tongue-type calcaneal fracture due to interposition of flexor hallucis longus.

We present a rare case of interposition of the flexor hallucis longus (FHL) tendon blocking percutaneous closed reduction of a displaced tongue-type calcaneal fracture, and necessitating open repositioning of the tendon and internal fixation through a single extensile lateral approach. Although not recognized until during surgery, with a high index of suspicion, preoperative diagnosis of this injury combination should be possible on high resolution CT, thus enabling better planning of the procedure. The presence of a small sustentacular fragment, especially if markedly displaced or rotated, should further alert the physician as to increased likelihood of such tendon entrapment within the fracture. In the literature, fracture fixation and extrication of the FHL tendon have been performed via either or both lateral and medial approaches. A medial approach may prove necessary when there is severe displacement or rotation of the sustentacular fragment. Arthroscopically assisted surgery may aid in disengaging the tendon from within the fracture site.