Commercially Available Guides Overestimate Socket Length During Anterior and Posterior Cruciate Ligament Socket Retrograde Drilling

Purpose

To objectively assess the accuracy of socket measurements taken during cruciate ligament reconstruction using a retrograde reaming technique.

Methods

Six complete knee sawbone specimens were used to ream anterior and posterior cruciate ligament sockets in the femur and tibia in a retrograde fashion using a standard retrograde reaming device. The longest and shortest sides of the sockets were measured using a ruler. One-sided Wilcoxon signed-rank sum tests were used to evaluate whether the actual measured socket length matched the estimated length set on the drill guide.

Results

One fellowship-trained surgeon reamed 24 total sockets in sawbone specimens using guides. Statistical analysis revealed a significant difference between the estimated measurement and the actual shortest tunnel length in each of the sockets. The median short side socket lengths were shorter than their respective intended depths by 4 mm for the femoral anterior cruciate ligament socket, 6 mm for the femoral posterior cruciate ligament socket, 6 mm for the tibial anterior cruciate ligament socket, and 4.5 mm for the tibial posterior cruciate ligament socket. All differences were significant at α = 0.05.

Conclusions

The estimated cruciate socket lengths reamed during ligament reconstruction using a retrograde reamer and standard intra-articular measuring instrumentation were greater than the actual measured socket lengths.

Clinical Relevance

Successful cruciate ligament reconstruction relies on accurate socket measurements. This study examined the accuracy of commercially available cruciate ligament socket drill guides and the implications for clinical practice, to include graft-tunnel mismatch and surface area available for healing. Surgeons may consider reaming slightly longer than estimated sockets when performing all-inside cruciate ligament reconstructions to ensure appropriate socket depth for graft fixation.