The term elbow dysplasia describes a group of developmental abnormalities affecting the canine elbow joint. These conditions are osteochondrosis of the medial humeral condyle, ununited anconeal process, elbow incongruity and fragmented medial coronoid process.
The most common form of elbow dysplasia that we see in practice is by far fragmented medial coronoid process. Recent research has shown that the actual fragment is only the “tip of the iceberg” of this very complex problem and this has led to better understanding of the condition and the framing of the term – Medial compartment disease.
This explains how a large percentage of cases do not show a satisfactory outcome by only removing the fragment of coronoid process from the joint. Finding cartilage erosion in symptomatic cases without fragmentation of the medial coronoid process confirms this suspicion.
A wide range of pathologies have been identified as part of medial compartment disease. This includes medial coronoid sclerosis, coronoid microfracture, coronoid fragmentation or fissuring and cartilage damage to the medial coronoid process. Thus medial compartment disease describes cartilage loss at the medial coronoid process and humeral epicondyle with or without fragmentation of fissuring of the medial coronoid process.
This paper will discuss the diagnosis and therapeutic approach to cases with medial compartment disease.
Radiographs will be the first diagnostic modality used when investigating the cause of front limb lameness in especially young to middle aged large breed dogs. Do not exclude any breed when confronted with this problem as we have done surgery on Staffordshire Bull Terriers and Shar Pei’s as well with medial compartment disease.
With multiple view radiography the sensitivity for finding fragmentation of the medial coronoid is between 10 and 60 %. We rely on secondary signs to more accurately predict the presence of medil compartment disease. The two most important features we use are marginal osteophytosis and ulnar subtrochlear sclerosis (STS). In 87 % of cases STS was the most significant finding in dogs under 12 months of age. Rounding or blurring of the medial coronoid process was seen in 67 % of cases over the age of 12 months.
The severity of the radiographic changes correlated strongly with the severity of arthroscopic cartilage damage. When secondary changes are severe on radiographs, the cartilage erosion will be of a higher grade. One can also find severe cartilage erosion in cases with mild radiographic changes.
CT is being used more and more to diagnose and characterize medial joint compartment pathology.
Arthroscopy is seen as the gold standard although one cannot see the underlying bone as with CT and using CT we cannot evaluate the level of cartilage damage like we can with using arthroscopy.
So in an ideal world all cases will have radiographs and CT done as well as arthroscopy as a minimum.
The Modified Outerbridge Score (MOS) is used to describe the cartilage damage found at arthroscopy.
Treatment groups consists of conservative therapy, reconstructive therapy and salvage procedures.
In the absence of prospective clinical trials, clinical decision making has become controversial. Personal experience and preference plays a big role in which treatment veterinarians decide to use. The advantages of arthroscopy includes reduced morbidity, minimally invasive which allows multiple joints to be treated and increased visualization of intra-articular structures. The disadvantages include increased costs, the surgeon’s learning curve and iatrogenic trauma that can be caused to cartilage and surrounding nerves.
Unfortunately there is no treatment for elliptical ulnar notch. Length discrepancies between the radius and ulna can best be addressed via one of a few osteotomies or ostectomies. These incongruencies are best measured using computed tomography but can also be judged on radiographs. A step of less than 2 mm between the radial head and the radial incisure is seen as normal.
Different opinions exists on which osteotomy to use when. The guideline we follow is for dogs between 5 and 7 months we will do a distal ulna ostectomy because the interosseus ligament is still immature. Between 7 and 9 months we perform dynamic proximal ulna osteotomies. Some surgeons prefer the long oblique ulna osteotomy at this stage. Generally after 9 months of age no osteotomies are performed on their own.
Decision making simplified
• < 9 months and fragment and Outerbridge 0-3 : Remove fragment and osteotomy
• < 9 months and fragment and Outerbridge 4-5 : Remove fragment, do SCO and osteotomy
• > 9 months and fragment and Outerbridge 0-3 : Remove fragment and debride
• > 9 months and fragment and Outerbridge 4-5 : Remove fragment and debride and SCO or PAUL or CUE or SHO or TER.
PAUL involves a specially designed lateral ulna plate made of titanium which abducts the proximal ulna. This works on the same principle as the proximal medial opening wedge osteotomy performed in people with medial joint disease of the knee. 4-6 degrees of abduction is needed to transfer load laterally. The paw is lateralized which moves weight bearing from the medial compartment to the lateral compartment. This allows cartilage resurfacing of the medial compartment and stops progression of microcrack formation. Clinical trials still need to be published on the success of this procedure. Surgeons that have been using this technique suggest that 80 % of cases at least have benefitted from this procedure. The titanium implants are expensive but morbidity is very low. This procedure was designed by Dr Ingo Pfeil from Germany. The Kyon company under Dr Tepic produce the implants. Research has shown that the load shift does occur in incongruent elbows. Limitations to the studies showed that more work had to be done especially prospective clinical trials.
Bi-Oblique Dynamic Proximal Ulnar Osteotomy
Described by Caron and Fitzpatrick the aim was to standardize the method for dynamic ulna osteotomy. Their study showed good improvement in lameness scores at 6 weeks and 6 month follow ups. The interosseus ligament was elevated cranially to facilitate proximal motion of the proximal ulna fragment.
The CUE is a resurfacing technique for the coronoid surface and medial humeral epicondyle. The advantage theoretically for this procedure over load shifting osteotomies and TER (Total Elbow Replacement) is that load is not shifted to the lateral compartment and all the natural motions of the elbow like supination and pronation are maintained. Down falls are that only a certain area can be resurfaced. We still await comparative studies between all of these techniques and conservative therapy with long term follow ups to help us with clinical decision making.
HD is a heritable condition with abnormal development of the femoral head and the acetabulum. Initial joint laxity leads to secondary changes in the bone and soft tissue structures of the coxofemoral joint. This degeneration leads to osteo-arthritis later. Although we have many options to treat HD and do so quite successfully, prevention of the condition through selective breeding has failed to eradicate the condition. Schemes to try and reduce the incidence of this condition evolves all the time and so does the approach to treating these case.
Diagnosis of hip dysplasia is fairly straight forward with radiographs being the main modality used to confirm and evaluate the extent of changes to the hip joints. It is important to remember how critical it is to be convinced that the hips are actually the sole cause of the clinical signs and owner complaint. This can be challenging in mature dogs with multiple radiographic abnormalities especially spinal pathology. In some cases further investigation with other modalities like MRI are needed to exclude spinal pathology.
When evaluating hips for possible surgery in young dogs, we take a number of radiographic views. Namely ventro-dorsal, “frog-leg”, lateral pelvic and DAR (dorsal acetabular rim) projection. Palpation of the hip joints under deep sedation or general anaesthesia is an important part of the examination. This gives us an idea of the laxity of the hips and also subluxation and reduction angles can be evaluated to either predict hip osteo-arthritis later in life or plan for possible triple pelvic osteotomy. The best predictor of hip osteo-arthritis at the age of 2 was the reduction angle of the joint evaluated at the age of 6 months. A reduction angle of more than 15 degrees was shown to be a very good predictor of hip osteo-arthritis later in life when measured at 6 months of age. One should keep in mind that there will be breed differences for example GSD’s have smaller reduction angles in general even when they develop OA. Rottweilers are more muscular and palpation could be falsely positive when evaluating the hip joints for laxity.
Basically 2 groups of options exist when faced with a clinical case of HD. Conservative therapy or surgical intervention.
Conservative therapy consists of weight control, exercise modification, physical therapy, pain control medication and joint modification therapy.
Surgical options include Juvenile Pubic Symphysiodesis, Triple pelvic osteotomy, Femoral head and neck excisional arthroplasty and Total hip replacement.
Conflicting reports exist with low level evidence on the effect of activity restriction. Some showed improvement in lameness assessments and other showed none.
Weight control and Dietary restriction
High level evidence showed a decrease in severity of radiographic changes and increased lifespan.
Modulation of degenerative joint disease
Good level of evidence exist for using polysulfated glycosaminoglycans in improving lameness scores but they were unable to show that this was an effective treatment for HD. Antioxidant therapy and Mesenchymal stem cell therapy both showed improvement in clinical cases. Outcome measures were subjective and we are awaiting objective outcome measurements in the future for these therapies.
Conflicting results were obtained using gold bead implantation at acupunctures sites. The placebo effect was also seen in these studies.
It can be very challenging to decide when to do surgery on hip cases and also which procedure to choose. There certainly is no “one size fits all” approach when it comes to HD. Approach differs widely between clinics and clinicians worldwide. The individual patient needs and owner expectations play a very big role. Finances is a very big factor in cases of HD because of the cost of total hip replacements compared to the other procedures and therapies available to the owner. A very thorough discussion must be held with the client when trying to guide them into making the right decision regarding the treatment of their pet.
Juvenile pubic symphysiodesis (JPS)
Usually performed in puppies between the age of 3 and 5 months. The objective being to slow down growth of the ventral aspect of the pelvis by obliterating the pubic symphysis using electro-cautery. This stimulates overgrowth of the dorsal acetabulae in order to reduce subluxation of the coxo-femoral joint. The difficulty with this procedure is to positively identify dogs with clinical signs of HD at this young age.
Triple pelvic osteotomy(TPO)
This procedure is performed on dogs between then age of 6 and 12 months usually. Dogs with hip laxity, positive Ortolani manoeuvres, reduction angles suggestive of normal acetabulae and no secondary arthritic changes make good candidates for this procedure. Very good long term results have been reported and are seen in practice if selection criteria are strictly adhered to.
Femoral head and neck excisional arthroplasty (FHO)
Probably the most commonly performed hip surgery worldwide. This procedure has been reported to give very good results in medium and small breed dogs. Pain relief is usually reliable but full functionality is not always achieved. The procedure is simple but still needs to be performed properly to avoid post-operative pain and complications. This is a salvage procedure and one should explain to the owner what the objective is with this procedure.
Total hip replacement (THR)
Readily available lately with excellent cementless systems now being preferred. Unfortunately a high cost procedure and also higher risk of complications due to the technical demand of the procedure itself. Very good success rate and close to normal return to function in most cases. A review of the long term outcome after Zurich cementless Total hip Arthroplasty in 439 cases revealed a 20 and 13 % complication rate in juvenile and adult dogs respectively. All cases were successfully revised except for 4 explants in total. The biggest factor in determining if a dog will have a complication was change in body condition score post operatively.
No surgical procedure has been proven to consistently return dogs to normal function when suffering from HD. Bergh and Budsberg reviewed peer-reviewed pubilcations between 1948 and 2012 on the surgical treatment of HD. This review found no evidence that FHO, TPO and intertrochanteric osteotomy or gold bead implantation could return dogs to normal function consistently. There was mixed evidence for THR and JPS. They looked at studies from an Evidence-based Medicine point of view and used the grading scheme for quality of evidence medicine.
References Tobias Surgery Textbook
Veterinary Surgery April 2016 p347-363
Veterinary Surgery January 2012 p2-9, 42-53
Veterinary Surgery July 2014 p501-506, 542-548
Veterinary Surgery February 2014 p155-165
Veterinary Surgery February 2015 p137-149, 174-179, 180-190, 195-199
Veterinary Surgery May 2015 p501-510, 511-520
Veterinary Surgery October 2014 p765-773, 804-813, 819-828