Block In Total Knee Arthroplasty Research Articles

The Optimal Analgesic Block for Total Knee Arthroplasty

Abstract Peripheral nerve block for total knee arthroplasty is ideally motor sparing while providing effective postoperative analgesia. To achieve these goals, one must understand surgical dissection techniques, distribution of nociceptive generators, sensory innervation of the knee, and nerve topography in the thigh.

Decreased risk of knee buckling with adductor canal block versus femoral nerve block in total knee arthroplasty: a retrospective cohort study.

BackgroundFemoral nerve (FNB) and adductor canal blocks (ACB) are used in the setting of total knee arthroplasty (TKA), but neither has been demonstrated to be clearly superior. Although dynamometer studies have shown ACBs spare perioperative quadriceps function when compared to FNBs, ACBs have been widely adopted in orthopaedic surgery without significant evidence that they decrease the risk of perioperative falls.MethodsAll patients who received single-shot FNB (129 patients) or ACB (150 patients) at our institution for unilateral primary TKA from April 2014 to September 2015 were retrospectively reviewed for perioperative falls or near-falls during physical therapy and inpatient care.ResultsThere were significantly more “near-falls” with documented episodes of knee buckling in the FNB group (17 vs 3, P = .0004). These patients’ first buckling episode occurred at an average of 21.1 hours postoperatively (standard deviation 5.83, range 13.83-41.15). There were no significant differences in pain scores between the 2 groups at any of the time periods measured; however, patients in the FNB group consumed significantly fewer opioids on postoperative day 1 than the ACB group (59 morphine equivalents vs 73, P = .004).ConclusionsA significantly higher rate of near-falls with knee buckling during in-hospital physical therapy was discovered in the FNB group. With increasing numbers of TKAs being performed on a “fast-track” discharge model, these results must be seriously considered, particularly in patients planning to go home the same day, to reduce the risk of postoperative falls. These data support the recent clinical data trend favoring ACB over FNB in orthopaedic surgery.

The Analgesic Efficacy of Sciatic Nerve Block in Addition to Femoral Nerve Block in Patients Undergoing Total Knee Arthroplasty

(Abstracted from Anaesthesia, 2016; 71(10):1198–1209) Placement of a sciatic nerve block can be challenging and carries some risk to a patient. Therefore, the inclusion of a sciatic nerve block for total knee arthroplasty requires further evidence supporting its efficacy.

Does Patient Perception Differ Following Adductor Canal Block and Femoral Nerve Block in Total Knee Arthroplasty? A Simultaneous Bilateral Randomized Study

BackgroundFemoral nerve block (FNB) has been used as part of the multimodal analgesia after total knee arthroplasty (TKA), but leads to weakness in the quadriceps muscles. Recently, adductor canal block (ACB) was reported to provide effective pain relief while sparing the strength of the quadriceps. This simultaneous bilateral randomized study investigated whether patients perceived differences between ACB and the FNB after same-day bilateral TKA. MethodsWe performed a prospective simultaneous bilateral randomized study in 50 patients scheduled to undergo same-day bilateral TKA. One knee was randomly assigned to ACB and the other knee was assigned to FNB. All ACB and FNB were performed using ultrasound-guided single-shot procedures. These 2 groups were compared for pain visual analogue scale, straight leg raising ability and knee extension while sitting, and motor grade. At postoperative week 1, the peak torque for the quadriceps muscle was measured in both knees with an isokinetic dynamometer. ResultsThere were no differences in pain levels between ACB and FNB during the entire study period. During the first 48 h after TKA, more of the knees that received ACB could perform straight leg raising and knee extension with greater quadriceps strength compared with FNB. However, no group differences in quadriceps functional recovery were found after postoperative 48 h and isometric quadriceps strength at postoperative 1 week. ConclusionThis simultaneous bilateral randomized study demonstrates that patients did not perceive differences in pain level, but experienced substantial differences in quadriceps strength recovery between knees during the first 48 h (Identifier: NCT02513082).

Adductor canal block versus femoral nerve block for total knee arthroplasty: a meta-analysis of randomized controlled trials

Femoral nerve blocks (FNB) can provide effective pain relief but result in quadriceps weakness with increased risk of falls following total knee arthroplasty (TKA). Adductor canal block (ACB) is a relatively new alternative providing pure sensory blockade with minimal effect on quadriceps strength. The meta-analysis was designed to evaluate whether ACB exhibited better outcomes with respect to quadriceps strength, pain control, ambulation ability, and complications. PubMed, Embase, Web of Science, Wan Fang, China National Knowledge Internet (CNKI) and the Cochrane Database were searched for RCTs comparing ACB with FNB after TKAs. Of 309 citations identified by our search strategy, 12 RCTs met the inclusion criteria. Compared to FNB, quadriceps maximum voluntary isometric contraction (MVIC) was significantly higher for ACB, which was consistent with the results regarding quadriceps strength assessed with manual muscle strength scale. Moreover, ACB had significantly higher risk of falling versus FNB. At any follow-up time, ACB was not inferior to FNB regarding pain control or opioid consumption, and showed better range of motion in comparison with FNB. ACB is superior to the FNB regarding sparing of quadriceps strength and faster knee function recovery. It provides pain relief and opioid consumption comparable to FNB and is associated with decreased risk of falls.

The ultrasound‐guided iPACK block with continuous adductor canal block for total knee arthroplasty

SummaryWe report a case of pre‐operative ultrasound‐guided local anaesthetic infiltration of the interspace between the popliteal artery and the capsule of the posterior knee (iPACK), in a 75‐year‐old male undergoing total knee arthroplasty. This was supplemented with postoperative adductor canal block using a continuous catheter technique. We assessed postoperative analgesia at rest and during active flexion of the knee, opioid consumption, motor and functional recovery, and patient satisfaction, for three postoperative days. This technique provided effective motor‐sparing analgesia, and was associated with excellent patient satisfaction.

The Anatomic Relationship of the Tibial Nerve to the Common Peroneal Nerve in the Popliteal Fossa: Implications for Selective Tibial Nerve Block in Total Knee Arthroplasty.

Background. A recently described selective tibial nerve block at the popliteal crease presents a viable alternative to sciatic nerve block for patients undergoing total knee arthroplasty. In this two-part investigation, we describe the effects of a tibial nerve block at the popliteal crease. Methods. In embalmed cadavers, after the ultrasound-guided dye injection the dissection revealed proximal spread of dye within the paraneural sheath. Consequentially, in the clinical study twenty patients scheduled for total knee arthroplasty received the ultrasound-guided selective tibial nerve block at the popliteal crease, which also resulted in proximal spread of local anesthetic. A sensorimotor exam was performed to monitor the effect on the peroneal nerve. Results. In the cadaver study, dye was observed to spread proximal in the paraneural sheath to reach the sciatic nerve. In the clinical observational study, local anesthetic was observed to spread a mean of 4.7 + 1.9 (SD) cm proximal to popliteal crease. A negative correlation was found between the excess spread of local anesthetic and bifurcation distance. Conclusions. There is significant proximal spread of local anesthetic following tibial nerve block at the popliteal crease with possibility of the undesirable motor blocks of the peroneal nerve.

Risk of Falling after Femoral Nerve Block for Total Knee Arthroplasty: Periprosthetic Fractures—A Serious Concern

Objective: Femoral nerve block (FNB) is a popular, minimally invasive postoperative pain management procedure followingtotal knee arthroplasty (TKA). Prolonged motor blockade has been associated with increased risk of fall. The primary objective of the present study was therefore, to evaluate the risk of falling or near falling for FNB in patients who underwent TKA. Materials and methods: After Institutional Review Board approval, prospective cohort (142) of patients was randomized into two groups: the intervention (FNB as an adjunct to analgesia) vs the control (standard treatment) at our hospital for unilateral primary conventional TKA. The risk of falling as assessed using Tinetti Gait and Balance Instrument and Timed Up and Go (TUG) test was evaluated on the day of hospital discharge, and 1, 2, and 3 months after TKA. All data were collected and critically analyzed and p < 0.05 was considered statistically significant. Results: Patients in FNB group displayed significant low visual analog scale (VAS) scores than control (p < 0.05). Thirty-seven patients (26.05%) reported falls in the 3 months after surgery. Patients who received FNB following TKA experienced an expected significant worsening of physical function and had increased risk of falling as evaluated by TUG test and Tinetti Gait and Balance Instrument (p < 0.05). Due to unexpected fall, eight patients (28.57%) in FNB group sustained periprosthetic fractures and two patients (22.2%) in control group had opening of arthrotomy. At 3 months, 55 patients in FNB group had reported postoperative neuritis. Significant delay in rehabilitation and early ambulation in patients received FNB, which in turn increases the risk of prolonged hospitalization (p < 0.05). Conclusion: The Tinetti and gait index and TUG test time showed increased risk of fall for the patients who received FNB owing to substantial functional deficits.

Defining the Location of the Adductor Canal Using Ultrasound.

Background and ObjectivesThe precise location of the adductor canal remains controversial among anesthesiologists. In numerous studies of the analgesic effect of the so-called adductor canal block for total knee arthroplasty, the needle insertion point has been the midpoint of the thigh, determined as the midpoint between the anterior superior iliac spine and base of patella. “Adductor canal block” may be a misnomer for an approach that is actually an injection into the femoral triangle, a “femoral triangle block.” This block probably has a different analgesic effect compared with an injection into the adductor canal. We sought to determine the exact location of the adductor canal using ultrasound and relate it to the midpoint of the thigh.MethodsTwenty-two volunteers were examined using ultrasound. The proximal end of the adductor canal was identified where the medial border of the sartorius muscle intersects the medial border of the adductor longus muscle. The distal end of the adductor canal is the adductor hiatus, which was also visualized ultrasonographically.ResultsThe mean distance from the anterior superior iliac spine to the midpoint of the thigh was 22.9 cm (range, 20.3–24.9 cm). The mean distance from the anterior superior iliac spine to the proximal end of the adductor canal was 27.4 cm (range, 24.0–31.4 cm). Consequently, the mean distance from the midpoint of the thigh to the proximal end of the adductor canal was 4.6 cm (range, 2.3–7.0 cm).ConclusionsIn all volunteers, the midpoint of the thigh was proximal to the beginning of the adductor canal, suggesting that an injection performed at this level is in fact a femoral triangle block.

Assessment for pain control efficiency of ultrasound guided adductor canal block in total knee arthroplasty: a report of 28 continuous cases

Objective: To assess the pain control efficiency of continuous adductor canal block in total knee arthroplasty. Methods: From October to December 2015, patients with severe knee osteoarthritis undergoing primary unilateral TKA were observed clinically.All of the patients received ultrasound-guided continuous adductor canal block after surgery.NPRS Pain score in rest and activity at 2, 6, 12, 24, 48 h after surgery were collected, preoperative and postoperative quadriceps strength at 24, 48 h were analyzed. Opioids consumption and anesthesia related adverse effects were also recorded. Results: All of the patients were enrolled. Rest pain control was fairly good(1.8±1.5), (2.4±1.5), (2.7±1.3), (2.7±1.7), (2.3±1.4) score, but the patients were not satisfied with activity pain control(3.1±2.1), (3.1±2.1), (4.2±2.2), (4.7±2.5), (6.2±2.4) score. There were statistically differences comparing the NPRS in rest pain with the score in activity, except for the results between each other at 6 hours (P=0.252>0.05)after surgery.The results showed no significant differences comparing quadriceps strengthpreoperatively with 24, 48 h postoperatively by repeated measurements variance analysis.Eight patients acquired additional use of dolantin once (100 mg/per time) within 24 h and among them three patients acquired once dolantin during 24 to 48 h. Eleven patients complained nausea postoperatively, one reported vomiting and one experienced xerostomia. Conclusion: Ultrasound-guided continuous adductor canal block can reduce resting pain after TKA, but has a limited effect in activity pain control.Quadriceps strength had been spared after ACB, which might performearly benefits in rehabilitation. ACB-related complications need further observation to be defined.

Preoperative ropivacaine with or without tramadol for femoral nerve block in total knee arthroplasty.

To compare the analgesic effect of preoperative ropivacaine with or without tramadol for femoral nerve block in total knee arthroplasty (TKA). 14 men and 46 women aged 59 to 80 years who were American Society of Anesthesiologists (ASA) grade I or II and were scheduled for TKA were randomised to receive preoperative femoral nerve block with 20 ml of 0.375% ropivacaine plus tramadol 0 mg (n=15), 50 mg (n=15), or 100 mg (n=15), or no preoperative femoral nerve block (control) [n=15]. Femoral nerve block was performed by a single anaesthesiologist before the standardised combined spinal epidural anaesthesia. Postoperatively, patientcontrolled analgesia was given. The visual analogue score (VAS) for pain at rest and on movement was recorded at 8, 12, 24, 48, and 72 hours. Passive knee range of motion (ROM) was measured at 24, 48, and 72 hours. The 4 groups were comparable in terms of age, gender, weight, ASA grade, and operating time. Compared with patients who received no femoral nerve block or ropivacaine alone, those who received femoral nerve block with 20 ml of 0.375% ropivacaine plus tramadol 50 mg or 100 mg recorded a lower VAS for pain at rest and on movement at 8 to 72 hours, longer sensory and motor block time, and lower demand, delivery, and total amount of patientcontrolled analgesia. The passive knee ROM at 24 to 72 hours was greater in patients with femoral nerve block than in those without. Preoperative femoral nerve block with 20 ml of 0.375% ropivacaine and 100 mg tramadol resulted in the best analgesic effect.

Analgesic Efficacy of Adductor Canal Block in Total Knee Arthroplasty: A Meta-analysis and Systematic Review.

The aim of this meta‐analysis and systematic review of randomized controlled trials (RCTs) was to evaluate the efficacy and safety of adductor canal block (ACB) for early postoperative pain management in patients undergoing total knee arthroplasty (TKA). Relevant manuscripts comparing ACB with saline or femoral nerve block (FNB) in TKA patients were searched for in the databases of PubMed, EMBASE, and Cochrane library. The outcomes assessed included cumulative analgesic consumption, pain at rest or during movement, ability to ambulate, quadriceps strength, and complications (nausea, vomiting or sedation). For continuous outcomes, pooled effects were measured using weighted mean difference (WMD) or standard mean difference (SMD), together with 95% confidence intervals (CIs). For outcomes without sufficient data for synthesis, qualitative interpretation of individual studies was summarized. Finally, 11 RCTs involving 675 patients met the inclusion criteria. The pooled results showed that ACB resulted in less postoperative analgesic consumption than saline (WMD, −12.84 mg; 95% CI, −19.40 mg to −6.27 mg; P < 0.001) and less pain at rest or during activity. No conclusions could be drawn regarding ability to ambulate and quadriceps strength, because only one study reported these variables. Most studies comparing ACB and FNB reported similar effects on postoperative analgesic consumption (WMD, −0.56 mg; 95% CI, −8.05 mg to 6.93 mg; P = 0.884) and pain; however, ability to ambulate and quadriceps strength were significantly better with ACB (SMD, 0.99; 95% CI, 0.04–1.94; P = 0.041). Additionally, ACB did not increase the rate of complications. Our results suggest that, compared with saline, ACB decreases analgesic consumption and offers short‐term advantages in terms of pain relief. Compared with FNB, ACB was associated with better ability to ambulate and quadriceps strength.

Utilization of Femoral Nerve Blocks for Total Knee Arthroplasty

BackgroundLittle information exists on national trends in the utilization of femoral nerve blocks (FNBs) in total knee arthroplasties (TKAs). We sought to describe the variations in anesthetic practice for FNB using the National Anesthesia Clinical Outcomes Registry. MethodsWe used the National Anesthesia Clinical Outcomes Registry to obtain patient, procedural, and provider information from January 2010 to June 2015. Case characteristics and clinical outcomes were compared using chi-square or t tests. We used logistic regression to identify associations between patient and case characteristics with anesthetic technique. ResultsOverall, 219,327 cases met the inclusion criteria, in which 72.7% and 27.3% did not or did receive a FNB, respectively. Patients less than 18 years old and those with higher American Society of Anesthesiologists physical status class (≥III) were less likely to receive a FNB. Surgeries performed after 5:00 PM also were less likely to receive the block. Cases with urban zip code had approximately 20% increased odds of receiving a FNB. General or neuraxial anesthesia types were not associated with utilization of FNB. FNB was associated with decreased percentage of extended recovery room stays and postoperative nausea and/or vomiting. ConclusionThere is considerable practice variation in the use of FNB for TKA, which is associated with various factors such as geographic location, time of day, and patient-specific comorbidities. Approximately one fourth of TKA cases include FNB. Overall, our study supports the clinical utility of FNB in TKA. As more data are compiled, it will be important to examine how national trends shift in the future.

Treatment of Bone Defect with Modular Metal Augmentation Using a Downsized Block in Total Knee Arthroplasty: Technical Note and Report of 17 Cases

In total knee arthroplasty (TKA), a treatment of bone defect varies depending on the location and extent of defect and requires proper surgical procedure. Metal augmentation is readily available for both femoral and tibial bone defects. We report the operative technique of modular metal augmentation using a downsized block for ambiguous proximal tibial and distal femoral bone defects in primary and revision TKA. Regarding bone defects, bone loss can be minimized by using a different size of metal augmentation, and suitable reinforcement for bone defects can be achieved. Once our technique is properly used, it will be very helpful in treating bone defects.

The Optimal Analgesic Block for Total Knee Arthroplasty.

Peripheral nerve block for total knee arthroplasty is ideally motor sparing while providing effective postoperative analgesia. To achieve these goals, one must understand surgical dissection techniques, distribution of nociceptive generators, sensory innervation of the knee, and nerve topography in the thigh.

Comparison of Local Infiltration Analgesia With Femoral Nerve Block for Total Knee Arthroplasty: A Prospective, Randomized Clinical Trial

BackgroundTotal knee arthroplasty (TKA) is usually associated with severe postoperative pain, which can prevent rehabilitation of patients' knee function and influence the satisfaction of surgery. Local infiltration analgesia (LIA) as a new method to managing postoperative pain has been applied in clinical practice recently. However, the safety and efficacy of LIA compared with femoral nerve block (FNB) in postoperative pain management of TKA still remains controversial. Thus, we conducted an original clinical trial to compare LIA and FNB. MethodOne hundred fifty-seven patients undergoing TKA were enrolled in a randomized, double-blind, single-center study. The patients received either FNB (group A) or periarticular infiltration of local anesthetic (group B). The morphine consumption used in patient-controlled analgesia after surgery, postoperative Visual Analogue Scale (VAS), Knee Society Score, and range of motion before and after surgery in both groups were analyzed, as well as the adverse effects. ResultsGroup A consisted 78 patients, and group B contained 79 patients. The patients' characteristics including age and body mass index had no significant difference (P > .05). Morphine consumption, VAS at rest, range of motion, and Knee Society Score were similar between the 2 groups. Our study showed group B, the local anesthetic group had less VAS with movement on postoperative day 1 (P = .01) than that of group A, which means a better pain control. Because of the study design, the surgery time showed no significant difference. Eighteen patients in group A and 21 patients in group B experienced mild-to-medium nausea or vomiting. One patient in group B had dizziness and one patient in group A suffered a neuropraxic injury to the femoral nerve. No urinary retention case was seen during inpatient days. There were no significant differences between the 2 groups about side effects. ConclusionsOur research showed that no significant differences were observed between the 2 treatment groups. LIA could provide a similar analgesic effect to FNBs with a low incidence of complications.

Local infiltration analgesia versus femoral nerve block in total knee arthroplasty: A meta-analysis

IntroductionLocal infiltration analgesia (LIA) and femoral nerve block (FNB) are both used for the pain management after total knee arthroplasty (TKA). Controversy still remains regarding the optimal technique for pain relief in patients undergoing TKA. The purpose of this meta-analysis was to compare the analgesia achieved with LIA and the one from FNB following TKA. HypothesisLIA achieves better pain control than FNB in patients with TKA. MethodsDatabases, including Pubmed, EMBASE, the Cochrane Library and Web of Science were comprehensively searched to identify studies comparing LIA with FNB for patients with TKA. Two reviewers independently selected trials, extracted data, and assessed the methodological qualities of included studies. Data were analyzed by RevMan 5.2. ResultsNine RCTs involving 782 patients were included. LIA achieved more rapid pain relief (VAS) at 6h postoperatively [SMD6h=−0.92, 95% CI (−1.38, −0.47)] than FNB. There were no significant differences at 24h and 48h [SMD24h=−0.03, 95% CI (−0.46, 0.40); SMD48h=0.28, 95% CI (−0.35, 0.91)], VAS with activity at 24h and 48h [SMD6h=−0.54, 95% CI (−1.62, 0.54); SMD24h=−0.22, 95% CI (−1.41, 0.96); SMD48h=−0.08, 95% CI (−0.52, 0.69)], opioid consumption at 24h and 48h [SMD24h=−0.24, 95% CI (−0.82, 0.34); SMD48h=0.15, 95% CI (0.25, 0.54)] and length of hospital stay [MD=−0.52, 95% CI (−1.13, 0.09)]. DiscussionLIA may be the better choice in the pain management of TKA for it could achieve fast pain relief and is easier to perform than FNB for patients with TKA. Level of evidenceLevel II, meta-analysis and systematic review.

Continuous Ultrasound-Guided Adductor Canal Block for Total Knee Arthroplasty

Hanson, Neil A.*; Allen, Cindy Jo*; Hostetter, Lucy S.†; Nagy, Ryan*; Derby, Ryan E.*; Slee, April E.‡; Arslan, Alex‡; Auyong, David B.* Author Information

Evaluation of the accuracy of patient-specific cutting blocks for total knee arthroplasty: a meta-analysis

Because published studies on the accuracy achieved with patient-specific guides during total knee arthroplasty (TKA) contradict each other, this systematic review and meta-analysis sought to compare radiological TKA outcomes when patient-specific cutting blocks (PSCB) were used to the outcomes when standard manual instrumentation was used. The meta-analysis was implemented according to PRISMA Statement Criteria. The primary endpoint was the hip-knee-ankle (HKA) angle, which represents the leg's mechanical axis. The accuracy of component placement in the coronal and sagittal planes, and the accuracy of femoral component rotation were also compiled. After testing for publication bias and heterogeneity across studies, data were aggregated random-effects modeling when necessary. Fifteen articles were included: 916 total knee arthroplasty cases in the PSCB group and 998 in the MI group. The mechanical axis did not differ between the two groups (weighted mean difference 0.07°; 95 % CI, -0.5° to 0.65°; p = 0.8). Risk ratio analysis revealed no protective effect of using PSCB relative to the appearance of HKA angle outliers (RR = 0.88; 95 % CI, 0.68-1.13; p = 0.3). There was a trend towards a protective effect with PSCB for the risk of femoral component outliers, but the opposite was observed for the tibial component. The implantation procedure was stopped in 30 cases because the surgeon-authors found excessive discrepancies between the intra-operative observations and the pre-operative plan. This meta-analysis found no evidence that using patient-specific cutting blocks provides superior accuracy to using manual instrumentation during TKA.

Continuous ultrasound-guided adductor canal block for total knee arthroplasty: a randomized, double-blind trial.

Adductor canal blocks have shown promise in reducing postoperative pain in total knee arthroplasty patients. No randomized, controlled studies, however, evaluate the opioid-sparing benefits of a continuous 0.2% ropivacaine infusion at the adductor canal. We hypothesized that a continuous adductor canal block would decrease postoperative opioid consumption. Eighty subjects presenting for primary unilateral total knee arthroplasty were randomized to receive either a continuous ultrasound-guided adductor canal block with 0.2% ropivacaine or a sham catheter. All subjects received a preoperative single-injection femoral nerve block with spinal anesthesia as is standard of care at our institution. Cumulative IV morphine consumption 48 hours after surgery was evaluated with analysis of covariance, adjusted for baseline characteristics. Secondary outcomes included resting pain scores (numeric rating scale), peak pain scores during physical therapy on postoperative days 1 and 2, quadriceps maximum voluntary isometric contraction, distance ambulated during physical therapy, postoperative nausea and vomiting, and satisfaction with analgesia. Eighty subjects were randomized, and 76 completed the study per-protocol. The least-square mean difference in cumulative morphine consumption over 48 hours (block-sham) was--16.68 mg (95% confidence interval, -29.78 to -3.59, P = 0.013). Total morphine use between 24 and 48 hours (after predicted femoral nerve block resolution) also differed by least-square mean -11.17 mg (95% confidence interval,: -19.93 to -2.42, P = 0.013). Intention-to-treat analysis was similar to the per-protocol results. Functional outcomes revealed subjects in the adductor canal catheter group had better quadriceps strength (P = 0.010) and further distance ambulated (P = 0.034) on postoperative day 2. A continuous adductor canal block for total knee arthroplasty reduces opioid consumption compared with that of placebo in the first 48 hours after surgery. Other outcomes including quadriceps strength, distance ambulated, and pain scores all show benefit from an adductor canal catheter after total knee arthroplasty but require further study before being interpreted as conclusive.