Objective: To study the outcome and surgical technique of patello-femoral joint arthroplasty (PFJ) for osteoarthritis of the knee.
Methods: From January 2010 to June 2012, 17 patients (24 knees) with patello-femoral compartmental osteoarthritis treated by PFJ were reviewed retrospectively. There were 2 male patients (4 knees) and 15 female patients (15 knees), with an average age of (64 ± 9) years (52-77 years) . The mean body mass index was (24 ± 3) kg/m² (18.0-30.1 kg/m²) . Patients were asked to return for follow-up examinations at 3, 6 months and at every year after PFJ. The range of motion (ROM), visual analogue scale(VAS), Hospital for Special Surgery score (HSS score) , Feller patella score, quadriceps muscle strength were evaluated before and after PFJ. The paired sample t-test and one-way analysis of variance (ANOVA) with replicate measures were used to determine whether there were statistically significant differences between the mean data.
Results: All of the patients were followed up for 18-47 months, with a mean time of (29 ± 10) months, 75.0% patients were satisfied with the outcome of this surgical procedure 1 year postoperative, and 87.5% were satisfied 2 years postoperative. HSS score was increased from 61 ± 11 to 90 ± 6 at the final follow-up (t = 12.24, P = 0.000). VAS score was reduced from 6.7 ± 1.0 to 2.4 ± 1.0 (t = 15.84, P = 0.000). The mean post-operative ROM of the knees was 126° ± 7° (t = 3.25, P = 0.003). Feller patella scores were 18.0 ± 3.2 before operation, and 18.5 ± 4.5, 19.7 ± 3.4, 24.0 ± 3.8, 26.0 ± 3.3, 26.6 ± 2.5 at 3, 6, 12, 24 months after operation, final follow-up, respectively. Quadriceps muscle strength were 3.9 ± 0.5 before operation, and 3.7 ± 0.5, 3.9 ± 0.5, 4.2 ± 0.5, 4.3 ± 0.5, 4.3 ± 0.5 at 3, 6, 12, 24 months after operation, final follow-up, respectively. Repeated measures ANOVA found significant time effects for Feller patella scores (F = 38.97, P = 0.000) and quadriceps muscle (F = 6.89, P = 0.000). Feller patella scores and quadriceps muscle strength were low at 3, 6 months after operation, with no significant differences compared with pre-operation data (P > 0.05). The improvements of Feller patella scores and quadriceps muscle strength after 6 months were of significant difference compared with pre-operation and postoperative 6 months data (t = 5.65-10.65 and t = 2.18-2.73, P < 0.05) . Three knee reported continuing pains with quadriceps muscle strength less than 4 level.
Conclusions: PFJ is an effective method for patello-femoral compartmental osteoarthritis with less trauma. The early term outcome of PFJ is encouraging. Quadriceps muscle strength should be enhanced.