Arthroscopic Surgery for Shoulder, Elbow and Stifle Problems
World Small Animal Veterinary Association World Congress Proceedings, 2007
Chris Preston
Animal Surgery Centre
Victoria, Australia

I have been involved with shoulder and elbow arthroscopy since 1998 and have found it superior to open arthrotomy in regards to visualization, postoperative complications, client acceptance and speed. The majority of forelimb lameness cases that are managed arthroscopically are discharged that same afternoon as day cases. This is practical and well received by clients. There is an associated learning curve, not only with the use of instruments and the development of triangulation skills but also in gaining familiarity with normal and abnormal joints. The elbow is certainly the place to start when learning.

Since Jan 2005, I have been exclusively performing stifle arthroscopy on cases that are having a TPLO procedure. Initially we had to perform arthrotomies on some of these patients to confirm what we thought we were seeing or to perform a meniscectomy. After a significant learning curve I never feel that conversion to an arthrotomy is required and feel that arthroscopic meniscal evaluation and meniscectomy is superior to open surgical evaluation and meniscal excision. I now find stifle arthroscopy reliable, fast and associated with no wound complications. I recommend that experienced arthroscopists consider routine use of arthroscopy for evaluation of all cruciate cases for these reasons.

Shoulder

Arthroscopic evaluation of the glenohumeral joint can be performed through a subacromial portal which allows thorough assessment of the entire joint. This is my default portal for exploration of painful shoulders, biceps cases as well as those with known OCD lesions.

Traditionally, patients are operated in lateral recumbency and an assistant holds the distal extremity to apply controlled traction and achieve a degree of joint distraction. I have used a wide strap to hold the thoracic cage to the patient table and have found this far better than simply having the assistant pull on the leg. The strap is placed under the chest and on both sides with the limbs of the strap dorsal to the patient's thoracic spine. These two ends of the strap are then secured to the side of the operating table where the arthroscopic tower will be positioned. The surgeon stands on the 'foot' side of the table with the assistant either on the left or right; whichever is more comfortable. The assistant is responsible for flexion, extension, traction, abduction and adduction.

A more recently described technique involves a hanging-limb style of setup with the patient positioned in dorsal recumbency. The foot is connected to the ceiling and the patient table lowered to use the patient's bodyweight to achieve distraction of the joint. I have used this approach and found it to be somewhat disorientating as the shoulder joint is upside-down. The distinct advantage of this technique is that a cranial and/or medial portal can be established as with human arthroscopy of the glenohumeral joint. This allow easy access to a craniomedial portal (between the biceps tendon and serratus ventralis). The patient must be positioned with the shoulders at the end of the table and with the head and neck reflected ventrolaterally, otherwise the surgeon will not be able to stand anterior to the shoulder joint. I have used this technique to successfully visualize a supraglenoid tuberosity fracture.

I use a manual fluid management system which relies on gravity flow through large diameter tubing rather than a mechanized fluid pump. There is a collapsible chamber that the assistant can compress to pressurize the system and this is typically performed when there is bleeding evident arthroscopically.

I typically inject up to 10 mls of saline through a 22 gauge hypodermic needle and keep that needle in position whilst the arthroscopic portal is created. I have had problems establishing this portal if the needle is extracted and a scalpel blade used 'blindly'. I have developed a technique where the needle acts as a direct guide to the joint position and I prefer to use a number 11 blade to cut directly in line with the needle that enters the joint.

For dogs up to 25-30 kgs, I use a 2.7mm arthroscope and for larger dogs a 4.0mm arthroscope. I have used a 2.4mm arthroscope in very small patients. I strongly feel that use of the 4.0mm scope provides a significantly larger image and makes triangulation easier due to a larger field of view. I do not feel that there is significantly higher morbidity associated with the use of the larger arthroscope and sheath in most of the OCD cases. I feel that establishment of shoulder portals is somewhat difficult and that generally a larger initial scalpel blade incision allows far easier placement of a blunt trocar and sheath.

I routinely explore the entire joint which includes assessment of:

1.  Humeral articular surface

2.  Glenoid articular surface

3.  Synovium

4.  Bicipital tendon

5.  Medial glenohumeral ligament

The most common diagnoses in my hospital are:

1.  Osteochondrosis

2.  Bicipital tenosynovitis

3.  Synovitis of unknown origin

Most OCD lesions involve a solitary, well defined cartilage flap lesion that can be easily extracted using grasping forceps through a caudal arthroscopic portal. This portal can be challenging to establish due to the deep location of the humeral head medial to the triceps musculature. I prefer to place a spinal needle (2-3 inches long) into the caudal aspect of the joint whilst looking for the needle trocar arthroscopically. The needle needs to enter the skin surface caudal and ventral to the subacromial arthroscopic portal. It is ideal to have the needle placed divergent to the line of the arthroscope. Once the tip of the needle has been visualized, the surgeon should assess its proximity to the OCD lesion when the needle is not being manipulated. It is better to reposition the needle and achieve a more accurate needle placement than to establish a portal that is poorly directed relative to the region of interest. Once the needle placement has been optimized, a large access incision is made to allow extraction of the flap in one piece. A system of cannulas can be used to maintain the caudal instrument and allow easier introduction of hand instruments.

A have used a craniolateral instrument portal to treat the majority of bicipital tendon tears. I initially probe the tendon to assess its integrity. Cutting hand instruments and / or monopolar radiofrequency units can be used to perform an arthroscopic tenodesis.

Elbow

Medial elbow arthroscopy can be performed with the patient in either lateral or dorsal recumbency. I have used both positions over the years and prefer patients to be positioned in lateral recumbency. I use a wooden block as a fulcrum to improve valgus stress on the elbow. The scrubbed assistant is instructed to extend, pronate and apply a valgus stress in order to improve access to the medial coronoid region of the ulna.

I use either a 2.4 or 2.7mm arthroscope in most elbows. I feel that in joints with effusion and more pain, I can generally upsize the arthroscope size and gain improved visualization. In some larger dogs with terrible joints I may attempt placement of a 4.0mm arthroscope. Again we use a manual fluid management system which seems to work fine.

Following fluid insufflation, I attempt to palpate the MCL and create a caudomedial arthroscopic portal and a craniomedial instrument portal. I do not use cannulated instrument portals.

I recognize a spectrum of FMCP pathology starting with minor cartilage fissuring and a so-called in situ FCP and progressing through to a displaced osteochondral fragment. I attempt to describe the degree of opposing humeral cartilage pathology as normal, mild, moderate or severe as well as comment on the degree of synovitis. I use hand curettes to debride in situ lesions and small joint grasping forceps to retrieve loose osteochondral fragments. Distal humeral OCD flaps are extracted using the same hand instruments.

I have used arthroscopic assistance to assess the position of UAP fragments when using a lag screw fixation technique.

Stifle

Aggressive tilting of the patient table with the head end elevated allows the knee to be lowered to a workable height for the surgeon. Rope is used to secure both thoracic limbs to the anaesthesia-end of the patient table. We also ensure that the patient's tailbase is located directly at the end of the patient table so that the surgeon can position themselves close to the stifle. A seated, sterile assistant is useful to setup instrumentation, position the limb and stress the joint into anterior tibial subluxation (drawer motion).

Use of pressurized, high flow irrigation as well as electrocautery is imperative for successful stifle arthroscopy. Over the years I have found that use of a 4.0mm arthroscope with a high flow cannula is a simple yet effective variation to enable high fluid flows at a reduced cost as a motorized fluid management system is not required. I feel that a 4.0mm arthroscope can be used in dogs greater than 25 kgs. The disadvantage of a larger arthroscope is that it can cause more trauma in the suprapatellar pouch and gutters. I have experimented with a number of different small joint electrocautery probe attachments and discovered a monopolar system with is available in zero, thirty and ninety degree options. I used these to cauterize bleeding tissue and vapourise the fat pad if it is inflamed as debridement of an inflamed fat pad using a motorized shaver causes problematic haemorrhage.

I use an egress cannula medially and use a short section (1m) of flexible tubing to allow the fluids to run directly into a bucket. I have found that without a motorized fluid management system, there is poor flow of fluids through a longer egress line. In human knee arthroscopy the arthroscope contains both ingress and egress channels and there is not a separate egress cannula. Certainly in many canine cases, I find that the majority of fluid egress occurs through a large and well positioned medial parapatellar instrument portal.

I make two stab incisions either side of the patellar tendon exactly half way between the patella and tibial tuberosity. If the portals are too high (proximal), the arthroscope and instruments may not be able to fully explore more caudal aspects of the femorotibial joint. If the portals are too low, the infrapatellar fat pad may cause unnecessary interference and obstruct the view of the operator. I do not insufflate the stifle prior to establishment of portals. I do not use cannulas to maintain medial parapatellar instrument portals.

A variety of appearances are compatible with a diagnosis of a partial ACL tear. I typically probe both ACL bands to fully assess the degree of tearing prior to making a decision regarding debridement of the ligament. I use a motorized shaver (oscillating mode) with suction at low speed to debride cruciate ligament tissue. With experience it is fast and accurate and there is minimal risk of iatrogenic PCL injury.

I use a blunt probe to assess the integrity of the meniscal horns. Often minor axial fraying of the lateral meniscus is noted. Effective probing of the caudal portion of the medial meniscus is difficult and requires experience especially in early partial ACL cases where a decision has been made to leave the ligament in place. I have developed a specific technique when performing a partial medial meniscectomy for 'bucket-handle' tears. The first step is to cut the lateral (cranial) attachment using a meniscotome. A small shaver is then used to debride the loose 'handle'. If this is not possible without injury to adjacent articular cartilage I use a very small right-angle monopolar radiofrequency probe to cut the medial attachment. Grasping forceps are then used to retrieve the released tear. Care is required to avoid the insertion of the PCL when cutting the caudal attachment of the meniscal tear.

Speaker Information
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Chris Preston
Animal Surgery Centre
Victoria, Australia


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