Posterior cruciate ligament repair seems safe with low failure rates but more high level evidence is needed: a systematic review

Specific fibre areas in the femoral footprint of the posterior cruciate ligament act as a major contributor in resisting posterior tibial displacement: A biomechanical robotic investigation

PURPOSE

Similar to the anterior cruciate ligament, the femoral footprint of the posterior cruciate ligament (PCL) is composed of different fibre areas, possibly having distinct biomechanical functions. The aim of this study was to determine the role of different fibre areas of the femoral footprint of the PCL in restraining posterior tibial translation (PTT).

METHODS

A sequential cutting study was performed on eight fresh-frozen human knee specimens, utilizing a six-degrees-of-freedom robotic test setup. The femoral attachment of the PCL was divided into 15 areas, which were sequentially cut from the bone in a randomized sequence. After determining the native knee kinematics, a displacement-controlled protocol was performed replaying the native motion, while constantly measuring the force. The reduction of the restraining force presented the percentage contribution of each cut, according to the principle of superposition.

RESULTS

The PCL was found to contribute 29 ± 16% in 0°, 51 ± 24% in 30°, 60 ± 22% in 60° and 55 ± 18% in 90°, to restricting a PTT. The fibre areas contributing the most were located at the proximal border of the PCL footprint, away from the cartilage, and directly adjacent to the medial intercondylar ridge (p < 0.05). Of these, one fibre area showed the highest contribution at all flexion angles. This area was located at the posterior half of the medial intercondylar ridge. No clear assignment of the areas to either the anterolateral or posteromedial bundle was possible.

CONCLUSION

An area towards the proximal and posterior part of the femoral PCL footprint was found to significantly restrain a posterior tibial force. Based on the data of this testing setup, a PCL graft positioned at the identified area may best mimic the part of the native PCL, which bears the most load in resisting a PTT force.

LEVEL OF EVIDENCE

No evidence level (laboratory study).

PCL injury following high energy trauma: associated injuries and postoperative complications "insights from a national registry study"

PURPOSE

The posterior cruciate ligament (PCL) is a vital knee stabilizer. While PCL injuries are rare, high-energy traumas can lead to total ruptures, with accompanying injuries requiring surgery. This study aims to investigate the demographics, concomitant injuries, and postoperative complications of patients who underwent PCL reconstruction due to high-energy trauma in a large patient sample.

METHODS

Patients who underwent PCL reconstruction from 2016 to 2022 were retrospectively evaluated using data from a nationwide personal health recording system. Patient demographics, injury mechanisms, associated fractures, soft tissue injuries, and postoperative complications were collected from patient notes, clinical visits, and surgical notes. Individuals with a PCL injury following high-energy trauma (car accident, falls from height, motorcycle accident) with a minimum follow-up of 1 year were included in the study.

RESULTS

The study included 416 patients with a mean age of 32.4 years. Isolated PCL injuries (n = 97, 23.3%) were observed less frequently than multiple-ligament injuries (n = 319, 76.7%). Most cases were treated with single-stage surgery (86.8%), while staged surgeries were performed in a minority of cases (13.2%). There was no relationship between trauma mechanisms and multiple-ligament involvement, accompanying injuries, or postoperative complications. Surgeries following car accidents were more likely to occur as staged surgeries (p = 0.014). Additionally, the complication rates for staged surgeries and younger patients (≤ 18 years) were significantly higher (p = 0.009).

CONCLUSION

High-energy trauma-induced PCL injuries are often associated with severe concurrent knee injuries with multiple ligament involvement. PCL reconstructions following car accidents are more likely to be staged. These findings highlight the importance of careful consideration in managing these cases to minimize complications, particularly in younger age groups.

LEVEL OF EVIDENCE

Level III.

Decreased posterior tibial slope is a risk factor for primary posterior cruciate ligament rupture and posterior cruciate ligament reconstruction failure: A systematic review

PURPOSE

To determine bony knee morphological factors associated with primary posterior cruciate ligament (PCL) rupture or PCL graft failure after PCL reconstruction.

METHODS

Three databases, namely MEDLINE, PubMed and EMBASE, were searched on 30th May 2023. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data such as receiver operating characteristic curve parameters, as well as p-values for comparisons of values between patients with PCL pathology and control patients, were recorded.

RESULTS

Nine studies comprising 1054 patients were included. Four studies reported that patients with PCL injury had flatter medial posterior tibial slopes (MTS) than controls, with mean values of 4.3 (range: 3.0-7.0) and 6.5 (range: 5.0-9.2) degrees, respectively. Two studies reported an MTS cutoff value ranging below 3.90-3.93° being a significant risk factor for primary PCL rupture or PCL graft failure. Two studies reported that shallow medial tibial depths were associated with primary PCL rupture, with mean values of 2.1 (range: 2.0-2.2) and 2.6 (range: 2.4-2.7) mm in PCL injury and control groups, respectively. Stenotic intercondylar notches and femoral condylar width were not consistently associated with PCL injuries.

CONCLUSION

Decreased MTS is associated with primary PCL rupture and graft failure after PCL reconstruction with values below 3.93° being considered as a significant risk factor. Less common risk factors include shallow medial tibial depth, while femoral condylar width and parameters with regards to the intercondylar notch, such as notch width, notch width index and intercondylar notch volume, demonstrated conflicting associations with primary or secondary PCL injuries.

LEVEL OF EVIDENCE

Level III.