RESURFACING VERSUS NONRESURFACING

Thirteen Level I-II studies and four meta-analyses found in the English literature examine the role of routine resurfacing of the patella. All of these studies compared two groups of patients with one group having routine resurfacing of their patellae and the other group routine retention of their patellae. These studies are examined paying specific attention to statistically significant differences in the incidence of patellofemoral complications or revisions, the incidence of anterior knee pain, and clinical or functional scores in these studies. There are a further 13 Level III-IV studies on the subject. However, this chapter examines only the Level I-II evidence available to make a recommendation.

Among the 13 Level I/II studies, only one found an inferior result in the resurfaced group favoring nonresurfacing as the preferred management. Eight studies found conflicting results within the same cohort over time or statistically nonsignificant results. Four studies found superior results in the resurfaced group (Table 89-1).

EVIDENCE FAVORING NEITHER ROUTINE RESURFACING NOR NONRESURFACING

Bourne and colleagues² report a series of 90 patients in a RCT with 50 knees in each group. At a minimum of 2 years, two nonresurfaced patellae had subsequent resurfacing for intractable knee pain. They found no statistically significant difference in Knee Society functional score, 30-second stair climbing, and the knee extension torque. The nonresurfaced patients had significantly less pain and better clinical rating. At the 8- to 10-year follow-up examination, Mayman and coauthors³ report results on the same group of patients. Twenty-nine patients had died leaving 71 patients to follow-up. One patient in the resurfaced group fell and fractured the patella, requiring a patellectomy. The clinical results had changed since the last report in favor of resurfacing. The incidence of anterior knee pain with walking and stair climbing was significantly less in the resurfaced group. More patients were either satisfied or extremely satisfied in the resurfaced group. At the minimum of 10 years review, Burnett and researchers⁴ report on 50 knees. From the original 90 patients, 7 refused to participate after enrollment in the study, 36 patients had died, and 2 patients could not attend the follow-up because of dementia and a stroke. Consequently, 45 patients and 50 knees remained to review. One more patient in the nonresurfaced group had had a subsequent resurfacing for anterior knee pain since the last review. No statistically significant difference was found between the groups regarding revision rates, Knee Society clinical rating and functional scores, patient satisfaction, anterior knee pain, and patellofemoral radiographic outcomes. The authors recommend a selective resurfacing approach.

Keblish and colleagues⁵ report on a quasirandomized, prospective, control trial of 52 patients who had bilateral TKR. Forty-four patients had osteoarthritis, six had rheumatoid arthritis, and two had post-traumatic osteoarthritis. All patients had a resurfacing on one side and nonresurfacing on the other. Fifty-one of the 52 had a metal-backed uncemented mobile-bearing patella, and 1 had a cemented all-polyethylene component. Only 58% (30/52) of patients were available for review. At a mean follow-up examination of 5.24 years, no statistically significant difference was found in subjective preference, performance on ascending and descending stairs, or the incidence of anterior knee pain. The authors conclude that nonresurfaced patellae could perform as well as resurfaced patellae.

Barrack and coauthors⁶ report on 118 knees in 86 patients at 2.5 years in a RCT. 10% of those in the non-resurfaced group had subsequent resurfacing because of pain. No patient in the resurfaced group had another operation. The statistical significance of this apparent difference in the incidence of reoperation was not reported. No statistically significant difference was found in regarding overall score, pain score, functional score, patient satisfaction, or the incidence of anterior knee pain. At the 5- to 7-year follow-up examination, Barrack and coauthors^6a report on 88 knees in 64 patients in the same cohort. One more patient in the nonresurfaced group had had a subsequent patellar resurfacing for anterior knee pain. Again, the statistical significance of the apparent difference in the incidence of reoperation was not reported. No statistically significant difference was found in any of the parameters previously examined. The conclusion of the authors was that the occurrence of anterior knee pain was unlikely to be related to whether the patella was resurfaced.

Peng and investigators⁷ report on 35 patients having bilateral TKR by a single surgeon in a quasi-randomized prospective study. A variety of implants was used: 30 NexGen (Zimmer, Warsaw, Indiana), 36 Miller-Galante II (Zimmer, Warsaw, Indiana), 2 PFC (Johnson & Johnson, Langhorne, Philadelphia), 2 Genesis (Smith & Nephew, Memphis, Tennessee). One patient in the nonresurfaced group had a patellar realignment for lateral subluxation after a fall. No statistically significant difference was found in Knee Society overall, clinical or function scores, incidence of anterior knee pain or reoperation, and no patient preference for either knee. No recommendation was made by the authors.

Campbell and researchers⁸ report on 100 TKRs in a RCT. At 10-year follow-up examination, 22 patients had died, 7 had dementia, 10 were lost to follow-up, and 3 had refused to participate because of poor health. Fifty-eight knees were therefore available to be reviewed. Two patients in the nonresurfaced group had undergone subsequent resurfacing for anterior knee pain. One patient in the resurfaced group had an arthroscopic lateral release for lateral tilting and anterior knee pain. No statistically significant difference was found in Knee Society score, Western Ontario and McMaster University Osteoarthritis Index, and specific patellofemoral-related questions. The authors conclude that they were not able to recommend routine resurfacing of the patella.

In all the articles previously mentioned in this section, no mention in any of the studies is made of a power analysis. Indeed, in each study, multiple outcomes are mentioned and no primary outcome is identified. Given that these trials were all negative, it is imperative that the reader know what the primary outcome of interest was and the sample size needed to achieve adequate power. Without this information, these negative trials give limited information to the reader. Given the numbers in these studies, it is most likely they were underpowered, rendering their conclusions that there is no difference between the treatment options open to question.