33rd Annual Scientific Meeting proceedings

Various pathologic canine shoulder conditions can result in lameness. Osteochondrosis dissecans is one possible cause. While typically diagnosed via radiographs, arthroscopy may be needed to aid in diagnosis and also allows treatment, such as removal of the osteochondral flap (Olivieri 2007, Wall 2015). The prognosis for shoulder OCD is good. Osteochondral defects of the glenoid can also be diagnosed and treated using arthroscopy (Bilmont 2018). Biceps injuries or luxations are best diagnosed with ultrasound or also arthroscopy. If indicated, biceps tendon release can easily be performed, permitting good function (von Pfeil 2020).

Working dogs often present with medial shoulder instability (MSI) (Cogar 2008; Franklin 2013). The causes of MSI include chronic repetitive activity, overuse or repetitive micro-trauma. Most commonly affected support structures include the joint capsule, the medial glenohumeral ligament (MGL) and the subscapularis tendon. Affected dogs may show signs as subtle as performance-related problems with a shortened stride or may present with severe lameness. Examination often reveals atrophy of the shoulder muscles, restricted range of motion, pain, muscle spasm and increased shoulder abduction angles (AA). The previously reported normal values (⁓30°; Cook 2005 a) for AA have been questioned as reliable values (Jones 2019), suggesting the normal AA-range may be higher. Indeed, in a recent study on 128 shoulders, AA reached up to 75ᴼ in normal shoulders (von Pfeil 2021). In addition to radiographs, CT or MRI and/or musculoskeletal ultrasound of the shoulder can be considered. Arthroscopy is considered the gold-standard for diagnostic purposes. Needle arthroscopy to diagnose MSI was reported for the first time in 2021 and compared to classic arthroscopy (von Pfeil 2021). No significant differences were found for surgery time, but existed for anesthesia time (35min shorter with needle arthroscopy) and invoice (38% lower with needle arthroscopy). Needle arthroscopy offers an alternative, safe technique to reliably diagnose canine MSI.

Treatment options of MSI include shockwave, followed by use of a Velpeau sling or of a shoulder stabilization system. Radiofrequency (RF) induced thermal capsulorrhaphy is used in some clinics for treatment of MSI. Importantly, only one retrospective study without a control group (Cook 2005 b) reports a positive outcome using RF. Similar success has not yet been reported by any other investigators in the last 18 years. Notably, RF in humans has resulted in numerous litigations as clinical signs worsened (Fenn 2007), possibly secondary to denaturation of collagen or chondrolysis (Jerosch 2007). Injections of corticosteroids, stem cells, stromal vascular fractions and platelet-rich plasma are commonly discussed, without current evidence of their benefit.

Placement of shoulder stabilization systems, followed by dedicated physical rehabilitation, is often sufficient to treat MSI and has been successfully applied by the author with even severe cases returning to athletic work at a highly competitive level. In contrast, one study evaluating the outcome of MSI-treatment found that surgical reconstruction was more likely to be associated with a successful outcome versus conservative treatment (Franklin 2013). Numerous limitations of this study include no predefined criteria for diagnosis, treatments, various surgeons and protocols, retrospective, non-blinded subjective outcome, incomplete follow-up. Prospective studies with are needed to suggest the most appropriate treatment algorithms.

Arthroscopically assisted placement of prosthetic ligaments may help to stabilize the shoulder joint in cases with severe instability. Recently, a ligamentoplasty using braided suture, anchored in the distomedial scapula, traveling through a bone tunnel in the humerus and secured on the lateral side of the humerus with a suture button, was reported in a cadaveric study (Llido 2023). There was no significant difference between initial and post-ligamentoplasty AA. A similar study describes the use of a minimally-invasive MGHL-reconstruction using a specific aiming device for the placement of threaded sutures, secured with buttons on the lateral aspects of the scapula and humerus (Rocheleau et al. 2023). Clinical studies on those techniques are pending as of yet.

Importantly, the use of those braided sutures (Tightrope, fiberwire) can be associated with bone tunnel widening (in human surgery, this effect from the TightRope has been associated with the term “cheese-wiring”), resulting in development of slack and thus negate the effect of treatment (Rochat, personal communication 2017) and increase the risk of infection (von Pfeil 2018). A survey among US-veterinary teaching hospitals revealed that 90% of those do not use this material for the aforementioned reasons (von Pfeil, non-published data). Similarly, based on responses from veterinary orthopedic surgeons collectively performing approximately 30,000 cranial cruciate ligament surgeries annually, braided multifilament suture material, as used in the TightRope, was perceived as having the highest incidence of major complications (86.1%), with infection being the biggest concern (von Pfeil 2018).

Rehabilitation is a mandatory part of any MSI-treatment. Depending on the degree of initial trauma and therapeutic approach, the time required for rehabilitation and time to return to normal function differ. Full activity is often not resumed until 4-6 months after diagnosis (Marcellin-Little 2007). With appropriate treatment, the prognosis for return to pre-injury activity is good in most dogs.

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