Summary

High risk of subjective failure after posterior cruciate ligament reconstruction

Abstract

Background

Posterior cruciate ligament (PCL) injuries are less common than anterior cruciate ligament injuries (ACL), and usually present with concomitant injuries. Outcomes after PCL reconstruction (PCLR) have been reported to be inferior to ACL reconstruction. Furthermore, combined ligament injuries have been reported to have inferior outcomes compared to isolated PCL injuries.

Purpose

To report on clinical outcomes and failure rates after PCLR and compare isolated PCLR with combined PCL injuries (more than one ligament reconstructed, including PCL).

Methods

All patients who underwent primary PCL reconstruction with or without concomitant ligament injuries registered in the Norwegian Knee Ligament Register from 2004 through 2019 were included. Patient reported outcomes with Knee Injury Osteoarthritis Outcome Scores (KOOS) were collected preoperatively, and postoperatively at two years and five years. Primary outcome measure was failure, defined as either revision surgery or a KOOS quality of life (QoL) subscale below 44. Revision rates were calculated using the Kaplan-Meier analysis and hazard ratios (HR) for revision were calculated using a multivariable Cox regression model.

Results

There were 585 primary PCL reconstructions registered in the period with 176 (30%) isolated PCL reconstructions and 409 (70%) combined reconstructions with a median follow-up time of 7.2 and 7.1 years, respectively. The most commonly used graft for PCL reconstruction was hamstring tendon autograft (69% for isolated PCL reconstruction, 49% for combined injuries). Allografts were used in 18.2% and 27.9% in isolated and combined PCLR, respectively. For isolated PCLR, graft size was recorded in 74 patients (<8 mm n=7, 8-10 mm n=52, >10 mm n=15). Most patients with PCL injuries had poor preoperative knee function as defined by a KOOS QoL <44 (91.2% for isolated PCLR and 84.4% for combined PCL injuries; p=0.08). There were significant improvements in KOOS subscores after surgery in both groups; however, subjective failure (KOOS QoL <44) of isolated PCLR (46.6%) and combined PCLR (44.7%) by two years was common (p=0.81). At five years the subjective failure rates (KOOS QoL <44) of isolated and combined PCLR were 49.3% and 36.7%, respectively (p=0.07). There was no statistically significant difference in revision rates between the groups at two or five years (2.4-3.8%). In a multivariable cox regression model, no factors were associated with revision at 2 years.

Conclusion

Patients who underwent PCLR had improved KOOS scores versus their preoperative state; however, the subjective failure rate was high but few patients underwent revision surgery. Patients with isolated PCL reconstructions can be expected to have similar failure rates as combined ligament reconstructions within the first two years. Future studies should evaluate the impact of recent advancements in PCL surgical and postoperative rehabilitation techniques on outcomes and failure rates.