[Unicompartmental-knee arthroplasty for treatment of lateral gonarthrosis: about 30 cases. Midterm results].
OBJECTIVE
The appropriate treatment when joint degeneration is limited to the lateral compartment remains controversial. Total-knee arthroplasty and alignment osteotomy are well studied for genu valgum. Little is known about the results with lateral-unicompartmental prostheses. The purpose of this work was to evaluate the midterm results in a series of lateral unicompartmental-knee prostheses.


METHODS
From 1985 through 2005, 35 lateral unicompartmental prostheses were implanted among a total of 703 unicompartmental arthroplasties. The indication for surgery was established on the findings of the plain X-rays and stress films to evaluate the medial compartment. Preoperatively, the overall misalignment was 6 valgus (range: 0 to 15). The mean preoperative IKS was 102 (range: 54 to 164). Implants used were: Miller-Galante (n=20), ZUK (n=4), Marmor (n=5) and Alpina (n=1). Mean polyethelene thickness was 9 mm (range: 6 to 17 mm). The IKS score was established preoperatively and at last follow-up. Outcome assessment searched for clinical, radiological and surgical criteria affecting survival. The Kaplan-Meier method was used to determine implant survival. Surgical revision for implant replacement or adjunction of a new implant was considered as the endpoint of implant survival.


RESULTS
Twenty-nine patients (30 knees) were reviewed at mean nine years (range: two to 22 years). Mean IKS at one year was 185. At last follow-up, mean IKS was 166 (range: 28 to 200). Overall misalignment without revision was 3 (range: -6 to +11). Five arthroplasties were revised, four for extension of the degenerative disease (two supplementary unicompartmental prostheses and two total-knee arthroplasties) and one for depression of the tibial plateau after manipulation for stiffness and revision by total-knee arthroplasty. Two associated procedures were performed: arthroscopy for pseudoblockage at two years and one patellar osteosynthesis for fracture at 10 years.


CONCLUSIONS
We have used unicompartmental lateral prostheses regularly since initiating our experience, but for rare indications (5% of all unicompartmental implantations). The lateral unicompartmental prosthesis is a surgical solution for isolated femorotibial degeneration. Results at mean nine years follow-up have been encouraging, that is, similar to those with a medial prosthesis.
Bertani
A
A
Service de Chirurgie Orthopédique et Traumatologique, HIA Laveran, Marseille, France. antoine_bertani@yahoo.fr
Flecher
X
X
Parratte
S
S
Aubaniac
J-M
JM
Argenson
J-N
JN
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D012189:Retrospective Studies; D013997:Time Factors