15.1 Introduction

Fracture of the femur in companion animals is common, often involves high force impact and is complicated by the extensive muscular envelope that surrounds the bone. The combination of traumatic hemorrhage at the fracture site and along the muscular planes, swelling and edema of the associated soft tissues, contraction of the muscular surround, fracture site displacement, and a propensity for the hip and stifle joint to lose their rotational alignment makes successful fracture repair challenging. The restoration of linear and rotational alignment of the femur along with the need to have a stable repair construct has lent the femoral fracture to bone plate repair. The evolution of plate design and capabilities has seen the locking plate (LP) become a staple of femoral fracture repair over the past 15 years. The ability to affix the bone screws securely to the bone plate and the fracture segments has, in the author’s opinion, improved the strength and durability of the fracture repair construct and decreased implant and therefore construct failure. The relative strength of the LP in comparison to the more traditional dynamic compression plate (DCP) with or without the addition of an intramedullary (IM) rod has also been investigated experimentally to determine the relative biomechanical qualities of the different construct types. A more recent trend in the orthopedic surgical field is away from the classic open reduction and internal fixation (ORIF) toward biological osteosynthesis and the development of minimally invasive plate osteosynthesis (MIPO) with a limited surgical approach and reduced iatrogenic trauma. This approach hopes to preserve bone vascularity, improve fracture consolidation, decrease infection rate and avoid the need for bone grafting and transforms the plate construct into an internal extramedullary splint. The MIPO treatment goal is the anatomic reconstruction of the articular area, if involved, and axis, rotation and length reestablishment for the metaphyseal‐diaphyseal area. The placement of a plate that bridges the fracture site and is only affixed to the femur proximally and distally with a limited number of bone screws is the underlying technical guideline. The establishment of sufficient fracture site stability with a degree of relative instability with MIPO is in contrast to the more traditional anatomic reduction and rigid fixation by bone plates with the goal of the technique being absolute fracture stability. The challenge of the MIPO technique is the decreased operative visualization of the fracture segments, the adjustment of the surgeon to less open visual cues to anatomic restoration and the need in many cases for intraoperative fluoroscopic examination. The term minimally invasive percutaneous plate osteosynthesis (MIPPO) is used to describe the use of small, multiple surgical skin incisions and the development of skin “windows” to access the bone surface. The plates are placed blindly up the bone shaft under the muscular layer to lie adjacent but not compressing the periosteum. In cases of concurrent articular fracture, the use of a transarticular approach and retrograde plate osteosynthesis (TARPO) is utilized to expose the articular surface by arthrotomy, reduce the articular fracture anatomically and implant the epiphysis area sufficiently to provide rigid stability to the articular fracture repair. The adjacent metaphyseal‐diaphyseal zone is then stabilized under MIPO guidelines.

Internal fixators can be expected to maintain but not obtain fracture reduction, so care must be taken to ensure adequate fracture reduction before insertion of the locked screws. The challenge to the trauma surgeon of reestablishing the length, axis and rotation of displaced femoral fractures during minimally invasive techniques is an ongoing area of both intraoperative imaging and surgical technique refinement.

15.2 Anatomy