Management of Fractures of the Long Bones of Eight Cats using External Skeletal Fixation and a Tied-in Intra-medullary Pin With a Resin-acrylic Bar
Massey University Veterinary Teaching Hospital, Institute of Veterinary, Animal and Biomedical Sciences, Massey University
Palmerston North, New Zealand
Case History and Clinical Findings
Eight feline patients with fractures of the humerus, femur or tibia were presented non-weight-bearing with varying degrees of soft tissue and concurrent injury. Five fractures were comminuted, two were open fractures and there was one malunion. Fracture repair was performed in each case using a low-cost resin-acrylic (Selley's Steel Knead-it) external skeletal fixator (ESF). An open, limited open or "open but do not touch" approach allowed intramedullary (IM) pinning of the major fragments, establishing axial alignment and countering bending stress. Application of the Type-Ia ESF using small diameter half-pins provided stabilisation against rotational and compressive forces. The half-pins and tied-in IM pin were incorporated into a composite bar with the resin acrylic.
Diagnosis and Results
Seven cats, including all 5 comminuted fractures, had uncomplicated fracture healing. Median time to complete removal of the construct was 7 (range 5 to 12) weeks. In the eighth cat an open fracture developed into a non-union, which required revision with a plate and bone graft. This cat and six others available for follow-up (median 6 months) were reported by their owners to enjoy normal activity. Two had a mild, intermittent lameness, one had a mild but persistent lameness and four were sound. Six out of seven owners rated the appearance of their pet's limb as normal.
The resin-acrylic ESF/tied-in IM pin construct was versatile and lightweight and allowed even highly comminuted non-load-sharing fracture configurations to be stabilised successfully using a biological strategy. Failure of the pin/acrylic interface did not occur and the frames provided sufficient strength as evidenced by healing without failure of the bar in these selected cases. A resin-acrylic ESF construct is inexpensive and affords the occasional orthopaedist the means to provide rotational stability when IM pinning has been used as the primary mode of fracture repair for short-oblique and transverse fractures. An extensive and costly clamp/bar inventory is not required, and there is greater flexibility for the orientation and placement of fixation pins than allowed by the traditional linear bar systems.