Decrease in Global Offset Leads to Complaints of Worsening of Valgus Knee Deformity After Total Hip Arthroplasty in Patients With Crowe Type IV Developmental Dysplasia of the Hip

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Radiology

Background:

• Conflicting evidence exists on the effect of total hip arthroplasty (THA) on valgus knee deformities in developmental dysplasia of the hip (DDH) patients.
• Identifying factors contributing to worsened valgus knee deformities post-THA in DDH is crucial for improving surgical outcomes.

Purpose of the Study:

• To investigate the factors associated with the worsening of valgus knee deformities after THA in patients with Crowe type IV DDH.
• To analyze radiographic parameters and their changes following THA in relation to knee deformity progression.

Main Methods:

• Retrospective case-control study of 51 patients (69 hips) with Crowe type IV DDH undergoing primary THA.
• Measurement of multiple radiographic angles (aLDFA, mLDFA, MPTA, HKA, TFA, JLCA, TJLA) and offsets (FO, AO, GO) before and after THA.
• Comparison of radiographic parameters between a case group (worsened valgus deformity) and a control group (no worsening).

Main Results:

• Both groups showed improved HKA after THA.
• The case group had significantly smaller pre-operative HKA, greater AO, and greater GO compared to the control group.
• Post-THA, GO decreased in both groups, and the case group experienced a significant increase in TJLA.

Conclusions:

• THA effectively improves HKA in DDH patients.
• A decrease in global offset (GO) post-THA may lead to an increased tibial joint line angle (TJLA), indicating pseudoprogression of valgus knee deformity.
• Restoring global offset (GO) during THA may mitigate the negative impact on TJLA and reduce patient complaints of worsening valgus knee deformities.