The Safe Zone for Hip Arthroscopy: A Cadaveric Assessment of Central, Peripheral, and Peritrochanteric Compartment Portal Placement (SS-01)

Abstracts Presented at the 27th Annual Meeting of the Arthroscopy Association of North America April 24-27, 2008 • Washington, D.C. The Safe Zone for Hip Arthroscopy: A Cadaveric Assessment of Central, Peripheral, and Peritrochanteric Compartment Portal Placement (SS-01). William J. Robertson, M.D., and Bryan T. Kelly, M.D. Summary: In this study, a standardized geometric pattern of eight skin incisions was used to reliably place 11 possible arthroscopic hip portals. These portals (4 central, 4 peripheral, and 3 peritrochanteric) confer no additional risk to nearby neurovascular structures. The distal lateral accessory and modified anterior portal pass through the Smith-Peterson interval in close proximity to a small terminal branch of the ascending Lateral Circumflex Femoral Artery. The greatest risk still comes from the proximity of the anterior portal to the Lateral Femoral Cutaneous Nerve. However, a slight lateralized location seems to provide substantial benefits. Purpose: Hip arthroscopy offers a minimally invasive approach to treat various disorders affecting the central, peripheral and peritrochanteric compartments of the hip. The advent of new surgical techniques has created a need for additional arthroscopic portals. This study evaluated 11 arthroscopic portals (4 central, 4 peripheral, 3 peritrochanteric) regarding their proximity to neurovascular structures and the extra-articular path taken prior to entering the intended compartment. Methods: Eleven standard portals were established in ten cadaveric hips, under arthroscopic and fluoroscopic visualization, using 3/16 inch Steinmann pins. Each hip was dissected and the relationship of the pins to the pertinent anatomy was recorded to the nearest 1 mm. Results: Only two of the eleven portals, the anterior and distal lateral accessory portals, came within 2 cm of a neurovascular structure prior to entering their respective compartment. The anterior portal placed the lateral femoral cutaneous nerve (LFCN) at risk, lying at an average 15.4mm (range, 1 to 28 mm) away. The distal lateral accessory portal lies an average 19.2mm (range, 5 to 42mm) from the ascending branch of the lateral circumflex femoral artery. Additionally, a small terminal branch of this artery courses an average 14.7mm (range,

2 to 33mm) and 10.1mm (range, 1 to 23mm) from the anterior portal and distal lateral accessory portal respectively. Conclusions: Additional portals are required for advanced arthroscopic hip procedures. The eleven portals in this study confer no additional risk to nearby neurovascular structures, with the greatest risk still coming from the proximity of the anterior portal to the LFCN. The Relationship of Traction Force, Traction Time, and Nerve Conduction Abnormalities During Hip Arthroscopy (SS-02). Scott Wotherspoon, M.D., and Timothy J. Doherty, M.D., F.R.C.P.C. Purpose: The purpose of this study is to investigate the relationships of traction force, traction time, and hip distraction to the development of nerve conduction abnormalities during hip arthroscopy. We attempt to define safe parameters for the use of traction during hip arthroscopy to minimize the complication of post-operative neuropraxia. Methods: Twelve patients with hip pathology and no known neurologic disorders underwent hip arthroscopy in the supine position. Traction forces applied to the operative leg were measured using a load-cell force transducer attached to the traction boot. Distraction of the hip joint was assessed using fluoroscopy. Nerve conduction studies of the tibial nerve was performed using a stimulator and surface electrodes measuring the latency of the Hoffmann reflex (Hlat reflex). Measurements of the traction force, distraction of the hip, and nerve conduction studies were performed and documented at baseline, at the time of traction application, and every fifteen minutes following. At the completion of the procedure, traction was released and nerve conduction studies were immediately performed and repeated in the recovery room one hour post-traction. Results: Nerve Conduction Studies- The mean baseline Hlat reflex was 30.4⫹/-2.3 milliseconds for all patients. Nerve conduction abnormalities were obtained in all twelve patients upon application of traction. Three

Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 24, No 6 (June, Suppl 1), 2008: pp e1-e37

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