Long femoral nails for neck of femur fractures and prophylactic fixation have a risk of anterior cortex perforation. Previous studies have demonstrated the radius of curvature (ROC) of a femoral nail influencing the finishing point of a nail and the risk of anterior cortex perforation. This study aims to calculate a patients femoral ROC using preoperative XR and CT and therefore nail finishing position.

We conducted a retrospective study review of patients with long femoral cephalomedullary nailing for proximal femur fractures (OTA/AO 31(A) and OTA/AO 32) or impending pathological fractures at a level 1 trauma centre between January 1, 2015 and December 31, 2020 with both full length lateral X-ray and CT imaging. Femoral ROC was calculated on both imaging modalities. Outcomes measured including nail finishing position, anterior cortex encroachment and impingement. The mean femoral ROC was 1026mm on CT and 1244mm on XR. CT femoral ROC strongly correlated with nail finishing point with a spearmans coefficient of 0.77. Additionally, femurs with a ROC <1000mm were associated with a higher risk of anterior encroachment (OR 6.12) and femurs with a ROC <900mm were associated with a higher risk of anterior cortex impingement (OR 6.47).

To our knowledge this is the first study to compare a measured femoral ROC to nail finishing position. The use of CT to measure femoral ROC and to a lesser extent XR was able to predict both nail finishing position and risk of anterior cortex encroachment. Preoperative XRs and CTs were able to identify patients with a small femoral ROC. This predicted patients at risk of anterior cortex impingement, anterior cortex encroachment and nail finishing position. We may be able to select femoral nails that resemble the native femoral ROC and mitigate the risk of anterior cortex perforation.

Summary Statement

This project proves that Patellofemoral (PF) joint degeneration is not a contraindication to medial unicompartmental knee replacement.

Introduction

Reported advantages of unicompartmental knee replacement (UKR) over total knee replacement (TKR) include better kinematics and less postoperative pain. The reported longevity of UKRs, regardless of design, still does not compare as favourably as that of TKR. Resurfacing-type UKR differ to other UKR in that they result in minimal bone resection.

Increased use of locking volar plates for distal radius fractures led to a number of reports in literature of flexor tendon injuries from impingement and attrition against hardware. Repair of the pronator quadratus is critical in preventing tendon injury. We present a pronator quadratus sparing approach to the distal radius.

The senior author has used a pronator quadratus sparing lateral pillar approach for for the past five years. A lateral incision is used over the radial styloid. The first dorsal compartment is released and APL and EPB tendons retracted. The underlying brachio-radialis tendon and insertion fascia is split and the palmar portion elevated off the distal radius with the pronator quadratus as a single contiguous sheet. The distal edge of the pronator quadratus is elevated from the wrist capsule by sharp dissection. The radial artery is protected by the retracted tissue.

Repair of the brachio-radialis tendon and insertion fascia is much more robust than that of the pronator quadratus covering the entire plate. Since 2004, the senior author has used the pronator quadratus sparing approach for volar plating of the distal radius, in 183 cases.

At last follow-up there were no instances of flexor tendon injury, which was considered to be one of the outcome measures and end-points. There was no impingement in the first dorsal compartment, except in two cases of lateral pillar hardware impingement from additional lateral pillar plate fixation through the same approach. Nine cases had minor persistent superficial radial nerve parasthesia. One case had a superficial wound infection requiring drainage. The repaired pronator quadratus formed a barrier protecting the plate. The infection was aggressively treated and the plate left in situ for three months till fracture union. Cultures from the retrieved plate showed no organisms.

Another implant had two of the locking screws back out. The pronator quadratus fascia was tented with an underlying haematoma. The fascia however only showed minimum screw penetration and no flexor tendon injury. Average wrist dorsiflexion was 72 deg and palmar flexion 65 deg.

Average pronation was 81 deg and average supination 69 deg. Supination range was slow to recover in younger patients. One explanation could be the tight pronator quadratus repair. Average PRWE and DASH scores were 19.

The quadratus sparing approach to the volar distal radius is easy to perform and protects the flexor tendons at the wrist. Cases demonstrated that an intact pronator quadratus can act as an effective barrier to prominent hardware and superficial infection. Supination range may be reduced by this approach due to a tight repair, though a palmar DRUJ capsule contracture may also be an explanation.