Primary constrained condylar knee arthroplasty without stem extensions for the valgus knee

Area of Science:

• Orthopedic Surgery
• Biomaterials Engineering

Background:

• Total knee arthroplasty (TKA) traditionally uses stem extensions, which can increase operative time, cost, and invasiveness.
• Stem extensions may also lead to complications like end-of-stem pain and complicate revision surgeries.

Purpose of the Study:

• To evaluate the midterm efficacy and safety of constrained condylar knee implants without stem extensions in primary TKA for severely deformed knees.
• To assess the rate of aseptic loosening and functional outcomes in this patient cohort.

Main Methods:

• Retrospective review of 70 primary constrained condylar knee implants without stem extensions (1998-2001) in 61 patients with severe valgus deformity (≥15 degrees).
• Follow-up of 55 knees in 49 patients for an average of 44.5 months.
• Outcome assessment using the Knee Society scoring system.

Main Results:

• Significant improvement in Knee Society and functional scores (from 34/40 to 93/74 points).
• No radiographic evidence of loosening or wear was observed.
• No cases of peroneal nerve palsy, flexion instability, or medial instability; one case of chronic patellar dislocation.

Conclusions:

• Constrained condylar knee implants without stem extensions offer effective pain relief and functional improvement in patients with severe valgus knee deformities.
• This technique demonstrates a low complication rate and no aseptic loosening at midterm follow-up, suggesting it is a viable alternative to stemmed implants.