In the worst cases, all of the cartilage on the medial (innermost) aspect of the joint is worn away, again both on the medial humeral condyle and the non-fragmented portion of the coronoid, resulting in what is now termed medial compartment disease. Unfortunately, this can occur in dogs as young as one year of age. In previous years, there was little that could be done for dogs with medial compartment disease. Now we have a procedure that looks very promising called Sliding Humeral Osteotomy or SHO.
As the name implies SHO involves performing a mid-humeral osteotomy (bone cut) and sliding the distal segment in a medial direction (fig 1). The sliding humeral procedure is the result of almost 10 years of laboratory research. These studies have demonstrated that the sliding humeral osteotomy significantly decreases joint pressure in the medial side of the elbow joint. Clinical studies have been performed to design a bone plate and screw system that results in superior osteotomy stability. The entire SHO procedure can be routinely performed in 30 – 60 minutes.
Almost any dog with medial compartment disease is a candidate for the SHO procedure. Any dog with forelimb lameness of uncertain cause warrants evaluation by a surgeon and possible arthroscopy of the elbow joint. An SHO may be performed regardless of patient age. The diagnosis of medial compartment disease requires arthroscopic evaluation and the SHO procedure may be performed at the same time.
Postoperative care for dogs undergoing an SHO is similar to that for dogs following TPLO. The patient should rest for the initial two weeks followed by leash walking for the next 6 to 10 weeks. Complete healing of the SHO usually requires 8 to 12 weeks after which time the patient may return to normal activity.
Careful clinical studies have been performed to evaluate the efficacy of this procedure. The majority of dogs undergoing SHO have decreased lameness by 12 weeks postoperatively with many dogs having no visual lameness at a 26-week evaluation. The owner satisfaction rate following SHO has been nearly unanimously positive.