Morbidity and Safety of Iliac Crest Reference Array Pins in Navigated Total Hip Arthroplasty: A Prospective Cohort Study

Navigated total hip arthroplasty (THA) can employ intra-osseous pins through a separate incision to secure reference arrays to the iliac crest. This study is the first to investigate the consequences of pin use in THA in vivo.

A prospective, consecutive series of 43 patients presenting for navigated THA were included. Two temporary 125 × 4 mm Schanz screws were inserted into the iliac crest for the attachment of a reference array. Telephone follow-up occurred at 6 and 12 weeks post-operatively. Patients were asked about pain, interference with daily activities, how often the wound was noticed, and duration of discomfort. Patient body mass index was recorded.

The follow-up rate was 100%. Pin site pain at any time post-operatively was reported by 24 patients (56%). This improved to 30%, 9%, and 2% at 3, 6, and 12 weeks, respectively. On average, pain lasted for 16 days total. The most common complaints after pain were clothing discomfort (23%), pain when wearing a belt (12%), or pain when mobilizing (9%). For the majority (98%) of patients, all symptoms had resolved by 12 weeks. There was no nerve injury, pin site fracture, infection, or screw breakage. Patients with body mass index greater than 30 kg/m²were up to 3 times more likely to experience pin site pain (P = .05), and had a longer duration of pain (P = .04).

Surgeons and patients should be aware that using navigational pins for array fixation carries low complication rates but often will cause pain and irritation that resolves in the short term.