Aim of Study: The aim of the study was to investigate the effect of muscle retractors on intramuscular pressure in the posterior spinal muscles during posterior spinal surgery.

Methods: Twenty patients undergoing posterior spinal surgery were recruited into this study and recordings of intramuscular pressure during surgery were performed using a Stryker® compartment pressure monitoring system, prior to insertion of retractors, 5, 30 and 60 minutes into surgery and on removal of retractors. Prior to and following use of the retractors, muscle biopsies were taken from the erector spinae muscle for analysis.

Results: A significant increase in intramuscular pressure (p< 0.001) was observed during surgery, with pressure rising from 7.1±4.1 mmHg pre-operatively to 26.4±16.0 mmHg 30 minutes into the operation. On removal of retractors, this pressure returned to or near to the original value. Analysis of muscle biopsies using calcium-activated ATPase birefringence revealed a reduction in muscle function following prolonged use of self-retaining retractors.

Discussion: This study demonstrates a substantial rise in pressure in the erector spinae muscle during posterior spinal surgery. Following retraction, marked changes were noted in the function of the muscles. This could be an important factor in the generation of operative scar tissue and post-operative dysfunction of the spinal muscles, and therefore, may be a cause of persistent back pain frequently observed in post-operative patients. Currently, this work is being extended to investigate the relationship between loss of muscle function and duration of retraction, and to study the long term implications of loss of muscle function with respect to surgical outcome and chronic back pain.

Objectives

Acetabular retractors have been implicated in damage to the femoral and obturator nerves during total hip replacement. The aim of this study was to determine the anatomical relationship between retractor placement and these nerves.

Introduction. The most difficult part of shoulder replacement. Important steps. Anaesthesia and patient position. Soft-tissue releases. Humeral bone removal. Retractor placement. Anaesthesia and Patient Position. Need full paralysis. Patient must be positioned laterally enough so that the scapula is unsupported. Arm is draped free so that it can be manoeuvred to find the position of optimal glenoid visualisation – usually this is slight extension, external rotation, and GH elevation to 45 – 60°. Soft-tissue Releases. Humeral side – make sure that the rotator interval is incised all the way to the glenoid margin and that the inferior capsule is released past the six o’clock position. Glenoid. Circumferential labral excision. Circumferential capsular release. Check for biceps glide. Humeral Bone Removal. Remove all osteophytes – inferior, anterior, and posterior. Make sure humeral osteotomy is through anatomic neck so that there is minimal bone protruding beyond the humeral cuff reflection. Retractor Placement. Retractors needed. Ring retractor (e.g., Fukuda) – both small and large. Other types of humeral head retractors (e.g., Carter Rowe). Reverse Homan x2. Single prong Bankart retractor. Large flat retractor (e.g., Darrach). Placement. Fukuda or Carter Rowe retractor – within the joint, levering on the posterior glenoid to displace humeral head posteriorly. Large Darrach – on anterior neck of scapula retracting subscapularis. Single prong Bankart or reverse Homan – superior glenoid under biceps anchor. Reverse Homan – inferior glenoid. Not always necessary