Relationship between patellofemoral morphology and anterior knee pain following tibial intramedullary nailing.

BACKGROUND

Anterior knee pain is among the most common complications after tibial intramedullary nailing (IMN), yet its etiology remains multifactorial and not fully elucidated. While surgical and technical factors have been widely studied, the role of intrinsic patellofemoral morphology has received limited attention.

METHODS

This retrospective study included 249 patients who underwent tibial IMN for diaphyseal tibial fractures between January 2018 and December 2023. Patients with pre-existing knee pathology or surgical complications were excluded. All surgeries were performed using a paratendinous approach, and patients were evaluated 12 months postoperatively. Anterior knee pain was assessed using the Visual Analog Scale (VAS), and knee function was evaluated with the Kujala score. Radiographic parameters, including Dejour classification of trochlear dysplasia, trochlear bump height, and Caton-Deschamps index (CDI), were measured on standardized lateral radiographs by two blinded observers.

RESULTS

Patients with significant anterior knee pain (VAS ≥ 4) showed a lower incidence of Dejour type A trochlea and higher trochlear bump heights compared to those with minimal pain (VAS < 4) (p < 0.05). Similarly, patients with poor functional outcomes (Kujala < 80) demonstrated higher rates of trochlear dysplasia (types B-D) and greater bump prominence. Although postoperative CDI values increased in both groups, indicating mild patellar elevation, this change did not correlate significantly with pain severity.

CONCLUSION

Patellofemoral morphological variations-particularly trochlear dysplasia and increased trochlear bump height-are significantly associated with postoperative anterior knee pain following tibial IMN. In contrast, patellar height changes appear less influential. Preoperative evaluation of trochlear morphology may assist in risk stratification and surgical planning to minimize postoperative anterior knee discomfort.

LEVEL OF EVIDENCE: 3b (individual casecontrol study).