Patellofemoral Arthroplasty Results in Better Time-weighted Patient-reported Outcomes After 6 Years than TKA: A Randomized Controlled Trial.

BACKGROUND: In a previous study, we reported the 2-year outcomes of a parallel-group, equivalence, randomized controlled trial (RCT; blinded for the first year) comparing patellofemoral arthroplasty (PFA) and TKA for isolated patellofemoral osteoarthritis (PF-OA). We found advantages of PFA over TKA for ROM and various aspects of knee-related quality of life (QOL) as assessed by patient-reported outcomes (PROs). Register data show increases in PFA revision rates from 2 to 6 years after surgery at a time when annual TKA revision rates are decreasing, which suggests rapidly deteriorating knee function in patients who have undergone PFA. We intended to examine whether the early advantages of PFA over TKA have deteriorated in our RCT and whether revision rates differ between the implant types in our study after 6 years of follow-up. QUESTIONS/PURPOSES: (1) Does PRO improvement during the first 6 postoperative years differ between patients who have undergone PFA and TKA? (2) Does the PRO improvement at 3, 4, 5, and 6 years differ between patients who have undergone PFA and TKA? (3) Do patients who have undergone PFA have a better ROM after 5 years than patients who have had TKA? (4) Does PFA result in more revisions or reoperations than TKA during the first 6 postoperative years? METHODS: We considered patients who had debilitating symptoms and PF-OA as eligible for this randomized trial. Screening initially identified 204 patients as potentially eligible; 7% (15) were found not to have sufficient symptoms, 21% (43) did not have isolated PF-OA, 21% (43) declined participation, and 1% (3) were not included after the target number of 100 patients had been reached. The included 100 patients were randomized 1:1 to PFA or TKA between 2007 and 2014. Of these, 9% (9 of 100) were lost before the 6-year follow-up; there were 12% (6 of 50) and 0% (0 of 50) deaths (p = 0.02) in the PFA and TKA groups, respectively, but no deaths could be attributed to the knee condition. There were no differences in baseline parameters for patients who had PFA and TKA, such as the proportion of women in each group (78% [39 of 50] versus 76% [38 of 50]; p > 0.99), mean age (64 ± 9 years versus 65 ± 9 years; p = 0.81) or BMI (28.0 ± 4.7 kg/m 2 versus 27.8 ± 4.1 kg/m 2 ; p = 0.83). Patients were seen for five clinical follow-up visits (the latest at 5 years) and completed 10 sets of questionnaires during the first 6 postoperative years. The primary outcome was SF-36 bodily pain. Other outcomes were reoperations, revisions, ROM, and PROs (SF-36 [eight dimensions, range 0 to 100 best, minimum clinically important difference {MCID} 6 to 7], Oxford Knee Score [OKS; one dimension, range 0 to 48 best, MCID 5], and Knee Injury and Osteoarthritis Outcome Score [KOOS; five dimensions, range 0 to 100 best, MCID 8 to 10]). Average PRO improvements over the 6 years were determined by calculating the area under the curve and dividing by the observation time, thereby obtaining a time-weighted average over the entire postoperative period. PRO improvements at individual postoperative times were compared for the patients who had PFA and TKA using paired t-tests. Range of movement changes from baseline were compared using paired t-tests. Reoperation and revision rates were compared for the two randomization groups using competing risk analysis. RESULTS: Patients who underwent PFA had a larger improvement in the SF-36 bodily pain score during the first 6 years than those who underwent TKA (35 ± 19 vs. 23 ± 17; mean difference 12 [95% CI 4 to 20]; p = 0.004), and the same was true for SF-36 physical functioning (mean difference 11 [95% CI 3 to 18]; p = 0.008), KOOS Symptoms (mean difference 12 [95% CI 5 to 20]; p = 0.002), KOOS Sport/recreation (mean difference 8 [95% CI 0 to 17]; p = 0.048), and OKS (mean difference 5 [95% CI 2 to 8]; p = 0.002). No PRO dimension had an improvement in favor of TKA. At the 6-year time point, only the SF-36 vitality score differed between the groups being in favor of PFA (17 ± 19 versus 8 ± 21; mean difference 9 [95% CI 0 to 18]; p = 0.04), whereas other PRO measures did not differ between the groups. At 5 years, ROM had decreased less from baseline for patients who underwent PFA than those who had TKA (-4° ± 14° versus -11° ± 13°; mean difference 7° [95% CI 1° to 13°]; p = 0.02), but the clinical importance of this is unknown. Revision rates did not differ between patients who had PFA and TKA at 6 years with competing risk estimates of 0.10 (95% CI 0.04 to 0.20) and 0.04 (95% CI 0.01 to 0.12; p = 0.24), respectively, and also reoperation rates were no different at 0.10 (95% CI 0.04 to 0.20) and 0.12 (95% CI 0.05 to 0.23; p = 0.71), respectively. CONCLUSION: Our RCT results show that the 2-year outcomes did not deteriorate during the subsequent 4 years. Patients who underwent PFA had a better QOL throughout the postoperative years based on several of the knee-specific outcome instruments. When evaluated by the 6-year observations alone and without considering earlier observations, we found no consistent difference for any outcome instruments, although SF-36 vitality was better for patients who underwent PFA. These combined findings show that the early advantages of PFA determined the results by 6 years. Our findings cannot explain the rapid deterioration of results implied by the high revision rates observed in implant registers, and it is necessary to question indications for the primary procedure and subsequent revision when PFA is in general use. Our data do not suggest that there is an inherent problem with the PFA implant type as otherwise suggested by registries. The long-term balance of advantages will be determined by the long-term QOL, but based on the first 6 postoperative years and ROM, PFA is still the preferable option for severe isolated PF-OA. A possible high revision rate in the PFA group beyond 6 years may outweigh the early advantage of PFA, but only detailed analyses of long-term studies can confirm this. LEVEL OF EVIDENCE: Level I, therapeutic study.

The Effect of Preoperative Intra-Articular Methylprednisolone on Pain After TKA: A Randomized Double-Blinded Placebo Controlled Trial in Patients With High-Pain Knee Osteoarthritis and Sensitization.

In a randomized, double-blind, placebo controlled trial, we investigated the postoperative analgesic effect of a single intra-articular injection of 40 mg methylprednisolone acetate (MP) administered 1 week before total knee arthroplasty (TKA). Forty-eight patients with high pain osteoarthritis (≥5 on a numeric rating scale during walk) and sensitization (pressure pain threshold <250 kPa), aged 50 to 80 years and scheduled for primary unilateral TKA under spinal anaesthesia were included. The primary outcome was the proportion of patients with moderate/severe pain during a 5-m walk test 24 hours postoperatively. Secondary outcomes included pain at 48 hours, during the first 14 days, sensitization (quantitative sensory testing with pressure pain threshold and wind-up from temporal summation), and inflammatory changes (systemic C-reactive protein, intra-articular interleukin [IL]-6). No difference in the proportion of patients with moderate/severe pain was found between MP/placebo groups at 24 hours (67% and 74%, χ2 = .2, P = .63, odds ratio = .7, 95% confidence interval = .2-2.8) or at 48 hours (57% and 68%, χ2 = .5, P = .46, odds ratio = .6, 95% confidence interval = .2-2.3), and no difference between groups in postoperative sensitization was found (P > .4) despite reduced preoperative intra-articular inflammation (IL-6) in the MP group versus placebo (median change in IL-6 = -70 pg/mL, interquartile range = -466 to 0 vs. 32 pg/mL, interquartile range = -26 to 75, P = .029). Alternative central or peripheral analgesic interventions in this high-risk group are required. PERSPECTIVE: Peripherally driven inflammatory pain and nociceptive changes before TKA has been suggested to be a cause for increased acute postoperative pain. However, preoperative intra-articular MP in patients with high pain osteoarthritis and sensitization did not reduce acute post-TKA pain or sensitization despite a preoperative reduction of intra-articular inflammatory markers.

The Isolated Effect of Adductor Canal Block on Quadriceps Femoris Muscle Strength After Total Knee Arthroplasty: A Triple-Blinded, Randomized, Placebo-Controlled Trial with Individual Patient Analysis.

BACKGROUND: Using peripheral nerve block after total knee arthroplasty (TKA), without impeding mobility, is challenging. We hypothesized that the analgesic effect of adductor canal block (ACB) could increase the maximum voluntary isometric contraction (MVIC) of the quadriceps femoris muscle after TKA. METHODS: We included 64 patients on the first postoperative day. Group A received an ACB with 30 mL ropivacaine 0.75% at t0 and with 30 mL saline 60 minutes later (t60). Group B received the treatment in the opposite order. The primary end point was the difference between groups in MVIC at t60, expressed as a percentage of postoperative preblock values. In this manner, the effect of the ACB could be isolated from the detrimental effect on muscle strength caused by the surgery. Secondary end points were differences between groups in mobility and pain scores. We planned a subgroup analysis dividing patients according to preblock pain scores during knee flexion. RESULTS: At t60, MVIC was higher in group A, with a median of 170% (95% confidence interval [CI], 147-231) of preblock values compared with 93% (95% CI, 82-98) in group B (P < 0.0001). No statistically significant differences were found in the Timed Up and Go (TUG) test. Three patients lost the ability to perform the TUG test in group A. At t60, differences in visual analog scale pain were in favor of group A; 12 mm (95% CI, 6-18) at rest, 14 mm (95% CI, 5-22) during knee flexion, and 18 mm (95% CI, 10-26) during the TUG test. CONCLUSIONS: ACB improves quadriceps femoris muscle strength, but whether this translates into enhanced mobility is not clearly supported by this study.

A comparison of epidural analgesia with combined continuous femoral-sciatic nerve blocks after total knee replacement.

Epidural analgesia remains the "gold standard" of pain relief after total knee replacement. However, peripheral nerve block is gaining popularity because the incidence of side effects may be reduced. Our study tests this postulate. Sixty patients were prospectively randomized to receive either epidural infusion or combined continuous femoral and sciatic nerve blocks. Ropivacaine 2 mg/mL plus sufentanil 1 mug/mL was given either epidurally or through the femoral nerve catheter, and ropivacaine 0.5 mg/mL was given through the sciatic nerve catheter using elastomeric infusers (delivering 5 mL/h for 55 h). The primary outcome measure was the total incidence of side effects (urinary retention and moderate to severe degrees of dizziness, pruritus, sedation, and nausea/vomiting on the first postoperative day). Intensity of motor blockade, pain at rest and on mobilization, and rehabilitation indices were also registered for 72 h. One or more side effects were present in 87% of patients in the epidural group whereas only 35% of patients in the femoral and sciatic block groups were affected on the first postoperative day (P = 0.0002). Motor blockade was more intense in the operated limb on the day of surgery and the first postoperative day in the peripheral nerve block group (P = 0.001), whereas the non-operated limb was more blocked in the epidural group on the day of surgery (P = 0.0003). Pain on mobilization was well controlled in both groups and there were no differences in the length of hospital stay. Rehabilitation indices were similar. The results demonstrate a reduced incidence of side effects in the femoral/sciatic nerve block group than in the epidural group on the first postoperative day.