Dynamic Proximal Ulnar Osteotomy (DPUO)

Introduction
Medial Compartment Disease (MCD) is a pathology which is part of elbow dysplasia, sometimes isolated, sometimes associated to other conditions (FCP, OCD).

In a preliminary study (1) the author showed that in dogs affected by MCD, simulating weight bearing under arthroscopic vision, the erosion of the medial humeral condyle and of the underlying ulna interfere during joint flexion and extension. The author described this condition as a humero-ulnar conflict (1) and hypothesized that performing a Dynamic Proximal Ulnar Osteotomy (DPUO) the two articular surfaces would have found a proper congruence, allowing the erosions to be repaired by fibrocartilage.

This study presents the author’s experience about 94 dogs with MCD treated with DPUO. In the first 18 cases a second-look arthroscopy was carried out 2.5 months after the osteotomy.

Materials and Methods
The elbow arthroscopies performed between January 2001 and January 2009 were reviewed and all the cases with MCD were selected. The criterion for inclusion in this study was treatment of MCD only by means of DPUO. If there were FCP or OCD fragments, these were removed. The criterion for exclusion were sclerosis of the subchondral bone, cartilage lesion of the lateral compartment and the presence of other orthopedic conditions.

In all the dogs a Robert Jones bandage was applied for the first 4 to 7 days, until bone dynamization was obtained; soon after a splint was implemented until consolidation of the osteotomy was reached. At the beginning of the study some cases had a second look arthroscopy after 2.5 months following initial surgery.

After osteotomy consolidation, clinical follow-ups were performed at 1, 2 and 12 months .

Results
94 cases were selected. Arthroscopic inspection showed erosion of the medial articular surfaces in all patients. The localization and extension of the erosion differed in some cases, suggesting that the forces generating erosion may have different force vectors . With flexion and extension of the joint, simulating weightbearing (1), it was always demonstrated that the pathologic joint cartilages of the medial humeral condyle and of the underlying ulna interfere during normal joint movements, creating a “conflict area” (humero-ulnar conflict).  [...]