Saithna A, Longo A, Leiter J, Old J, Macdonald PM. Southport & Ormskirk Hopsitals, UK, and the Pan Am Clinic, Canada

BACKGROUND

There is increasing evidence to support a subpectoral over a suprapectoral tenodesis location. Subpectoral tenodesis can be performed with a variety of different techniques (uni or bicortical button, tenodesis screw, suture anchors) but none has been clearly demonstrated to be superior to another with respect to biomechanics or clinical outcomes. In the absence of high quality evidence to guide the selection of a particular surgical technique the most important consideration should be the safety profile of the procedure.

OBJECTIVES

A number of cadaveric studies have evaluated the risk of neurological injury with subpectoral tenodesis using a bicortical button but there has been quite some variability in the reported proximity to the major nerves. Furthermore, in some cases cadaveric and clinical studies have reported iatrogenic injury and certainly this is a cause for concern. Some of this variability in reports of proximity to important structures is probably due to small sample sizes. It is therefore appropriate that further study is performed to add to this existing data. The aim of this study is to evaluate the risk of neurological injury from the placement of a bicortical guidewire during subpectoral biceps tenodesis.

RESULTSThe mean age was 73 years (range 44-96 years) and there was an equal distribution of right and left-sided limbs.

The mean distances from the guidewire to the respective nerves was as follows: axillary nerve posteriorly; 15.7 mm (10-22 mm), axillary nerve laterally; 18.7 mm (12-22 mm), radial nerve posteriorly; 26.2 mm (16-35 mm), radial nerve medially; 25 mm (16-32 mm), musculocutaneous nerve; 20.1 mm (12-26 mm). The chart below demonstrates the range of proximities to the respective nerves (AP: Axillary nerve posteriorly, AL: Axillary nerve laterally, RP: Radial nerve posteriorly, RM: Radial nerve medially, M: Musculocutaneous) in the current study (shaded boxes), compared to the ranges reported in all other published series (lines) [data included from refs 1-5 below].

The most important finding is that the axillary nerve posteriorly was within 10mm of the guidewire in at least one specimen in our study and in direct physical contact with the wire in other studies demonstrating a high risk of iatrogenic injury.

CONCLUSIONS REFERENCES

METHODS

The study was awarded health research ethics board approval. 10 fresh frozen forequarter cadaver specimens with intact distal extremities were evaluated after being thawed for a minimum of 24 hours.  A 3 cm incision was centred over the lower border of a normally tensioned pectorals major. The fascia over the coracobrachialis and biceps muscle bellies was incised and blunt finger dissection was used to identify the tendon and the bicipital groove. Non-levering retractors were then placed on bone to clearly expose the intended site of tenodesis. This was located in the bicipital groove, 1 cm above the lower border of the pectoralis major muscle. A 2.7 mm guidewire was passed from the bicipital groove anteriorly to posteriorly, through both cortices, with a trajectory that was perpendicular to the long axis of the humerus and parallel to the rotational axis of the forearm. A full, open dissection was then performed to identify the neurological structures. Digital calipers were used to record the closest distances from the guidewire to the nerves in their susceptible locations

Although there has been some disagreement in the literature regarding the proximity of a bicortical guidewire to the axillary nerve posteriorly, the results of this study concur with reports from several other authors and demonstrate that this nerve is at risk of iatrogenic injury when using a bicortical technique. A unicortical technique avoids this risk and has not been shown to be inferior biomechanically.

Surgeons should consider a unicortical technique and if they use a bicortical technique they should be aware of the diameter of button that they use when evaluating the data reported in this study (distance from guidewire only reported in this study i.e. button diameter not accounted for) and the risk of iatrogenic injury.

1.Arora AS, Singh A, Koonce RC (2013) Biomechanical Evaluation of a Unicortical Button Versus Interference Screw for Subpectoral Biceps Tenodesis. Arthroscopy 29:638–6442. Dickens JF, Kilcoyne KG, Tintle SM, Giuliani J, Schaefer RA, Rue J-P (2012) Subpectoral Biceps Tenodesis: An Anatomic Study and Evaluation of At-Risk Structures. Am J Sports Med 40:2337–23413. Ding DY, Gupta A, Snir N, Wolfson T, Meislin RJ (2014) Nerve Proximity During Bicortical Drilling for Subpectoral Biceps Tenodesis: A Cadaveric Study. Arthroscopy 30:942–9464. Lancaster S, Smith G, Ogunleye O, Packham I (2014) Proximity of the axillary nerve during bicortical drilling for biceps tenodesis. Knee Surg Sports Traumatol Arthrosc DOI 10.1007/s00167-014-3214-z5. Sethi PM, Vadasdi K, Greene RT, Vitale MA, Duong M, Miller SR (2015) Safety of open suprapectoral and subpectoral biceps tenodesis: an anatomic assessment of risk for neurologic injury. J. Shoulder Elbow Surg. 24:138–142

A Cadaveric Assessment Of The Risk Of Nerve Injury During Open Subpectoral Biceps Tenodesis Using a Bicortical Guidewire

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