The Intramedullary Cortical Button Technique for Distal Biceps Tendon Repair

Safe Drill Trajectory for Anatomic Repair of Distal Biceps Tendon Through a Single Incision: A Cadaveric Study

PURPOSE

We sought to determine the safest drill trajectory to avoid injury to the posterior interosseous nerve (PIN) when performing a repair of a distal biceps tendon to an anatomic location through an anterior, single-incision approach using cortical button fixation.

METHODS

A standard anterior approach was performed in 10 cadaveric specimens to expose the distal biceps attachment. Three drill holes were made in the radial tuberosity from the center of the anatomic footprint for the distal biceps tendon insertion with the forearm fully supinated. Holes were made in 30° distal, transverse, and 30° proximal directions. Each hole was made by angling the trajectory from an anterior to posterior and ulnar to radial direction, leaving adequate bone on the ulnar side to accommodate an 8-mm tunnel for the purpose of docking the biceps tendon into bone. The proximity of each drill trajectory to the PIN was determined by making a second incision on the dorsum of the proximal forearm. A K-wire was passed through each hole, and the distance between the PIN and K-wire was measured for each trajectory.

RESULTS

The distally directed drill hole placed the trajectory wire closest to the PIN (mean distance, 5.4 mm), contacting the K-wire in 3 cases. The transverse drill trajectory resulted in contact with the PIN in 1 case (mean distance, 7.6 mm). The proximal drill trajectory appeared safest, with no PIN contact (mean distance, 13.3 mm).

CONCLUSIONS

In this cadaveric study, the proximal drill trajectory resulted in the widest clearance from the PIN.

CLINICAL RELEVANCE

When performing repair of a distal biceps tendon to the anatomic location on the tuberosity, the drill trajectory from the center of the biceps footprint should be radial and proximal to provide the greatest separation between the drill guide and the PIN.

Subcortical Backup Tibial Fixation in Anterior Cruciate Ligament Reconstruction Has Similar Maximal Strength to Current Techniques

Purpose

To evaluate the biomechanical profile of subcortical backup fixation (subcortical button [SB]) in anterior cruciate ligament (ACL) reconstruction as compared with a bicortical post and washer (BP) and suture anchor (SA) when used with interference screw (IS) primary fixation and to evaluate the utility of backup fixation for tibial fixation with extramedullary cortical button primary fixation.

Methods

Fifty composite tibias with polyester webbing-simulated graft were used to test constructs across 10 methods. Specimens were separated into the following groups (n = 5): 9-mm IS only, BP (with and without graft and IS), SB (with and without graft and IS), SA (with and without graft and IS), extramedullary suture button (with and without graft and IS), and extramedullary suture button with BP as backup fixation. Specimens were tested under cyclic loading and then loaded to failure. Maximal load at failure, displacement, and stiffness were compared.

Results

Without a graft, the SB and BP had similar maximal loads (802.46 ± 185.18 N vs 785.67 ± 100.96 N, P = .560), and both were stronger than the SA (368.13 ± 77.26 N, P < .001). With graft and an IS, there was no significant difference in maximal load between the BP (1,461.27 ± 173.75 N), SB (1,362.46 ± 80.47 N), and SA (1,334.52 ± 195.80 N). All backup fixation groups were stronger than the control group with IS fixation only (932.91 ± 99.86 N, P < .001). There was no significant difference in outcome measures between the extramedullary suture button groups with and without the BP (failure loads of 721.39 ± 103.32 N and 718.15 ± 108.61 N, respectively).

Conclusions

Subcortical backup fixation in ACL reconstruction has similar biomechanical properties to current methods and is a viable backup fixation alternative. Backup fixation methods work synergistically with IS primary fixation to strengthen the construct. There is no advantage to adding backup fixation to extramedullary button (all-inside) primary fixation when all suture strands are secured to the extramedullary button.

Clinical Relevance

This study provides evidence that subcortical backup fixation is a viable alternative for surgeons during ACL reconstruction.

Intramedullary Unicortical Button and All-Suture Anchors Provide Similar Maximum Strength for Onlay Distal Biceps Tendon Repair

PURPOSE

To evaluate the biomechanical profile of onlay distal biceps repair with an intramedullary unicortical button versus all-suture anchors under cyclic loading and maximal load to failure.

METHODS

Twenty paired fresh-frozen human cadaveric elbows were randomized to onlay distal biceps repair with either a single intramedullary button or with two 1.35-mm all-suture anchors. A 1.3-mm high tensile strength tape was used in a Krackow stitch to suture the tendons in both groups. Specimens and repair constructs were loaded for 3,000 cycles and then loaded to failure. Maximum load to failure, mode of failure, and construct elongation were recorded.

RESULTS

Mean (± standard deviation) maximum load to failure for the unicortical intramedullary button and all-suture anchor repairs were 503.23 ± 141.77 N and 537.33 ± 262.13 N (P = .696), respectively. Mean maximum displacement after 3,000 cycles (± standard deviation) was 4.17 ± 2.05 mm in the button group and 2.06 ± 1.05 mm in the suture anchor group (P = .014). Mode of failure in the button group was suture tape rupture in 7 specimens, failure at the tendon-suture interface in 2 specimens, and button pullout in 1 specimen. Anchor pullout was the mode of failure in all suture anchor specimens. There were no tendon ruptures or radial tuberosity fractures in either group.

CONCLUSIONS

This study demonstrates that onlay distal biceps repair with 2 all-suture anchors has similar maximum strength to repair with an intramedullary button and that both are viable options for fixation.

CLINICAL RELEVANCE

All-suture anchors and unicortical intramedullary button have similar maximum strength at time zero. Both constructs provide suitable fixation for onlay distal biceps repair.