Influence of Total Knee Arthroplasty on Patellar Kinematics and Patellofemoral Pressure.

BACKGROUND: Patellofemoral complications are one of the main problems after total knee arthroplasty (TKA). The design of the TKA component may affect the patellar biomechanics, which may be associated with this postoperative complication. The purpose of this study was to assess the influence of TKA and prosthesis designs on the patellar kinematics and patellofemoral pressure. METHODS: Using fresh-frozen cadavers, we measured the patellofemoral pressure, patella offset, and patella tilt in the following 4 conditions: normal knee (patella replacement only), cruciate-retaining TKA, condylar-stabilizing TKA, and posterior-stabilized TKA. RESULTS: The patellofemoral pressure increased significantly after the cruciate-retaining TKA and condylar-stabilizing TKA compared with the normal knee. The patella offset in the normal knee decreased with increasing knee flexion angles, while the patella offset in the TKA knees did not change significantly through the full range of motion. The amount of lateral patella tilt in the normal knee was significantly larger than the TKA knees in the full range of motion. CONCLUSION: Although the femoral components are designed to reproduce an anatomical patellar tracking, the physiological patellar kinematics were not observed. Relatively high patellofemoral pressure and kinematic change after TKA may be associated with postoperative complications such as the anterior knee pain.

Femoral nerve block-sciatic nerve block vs. femoral nerve block-local infiltration analgesia for total knee arthroplasty: a randomized controlled trial.

BACKGROUND: The use of femoral nerve block (FNB) combined with sciatic nerve block (SNB) after total knee arthroplasty (TKA) has recently become controversial. Local infiltration analgesia (LIA) has been reported to be effective for postoperative TKA pain control. We aimed to assess whether LIA with continuous FNB is as effective as SNB combined with continuous FNB. METHODS: This was a prospective, randomized, single-center, observer-blinded, parallel group comparison trial of 34 American Society of Anesthesiologists (ASA) physical status 1-3 patients who underwent TKA and fulfilled the inclusion and exclusion criteria. Patients were randomized into two groups: a periarticular LIA and FNB group (group L, n = 17), and an SNB and FNB group (group S, n = 17). In both groups, participants received FNB with 20 mL of 0.375% ropivacaine, and 5 mL h(-1) of 0.2% ropivacaine after surgery. In group L, participants received 100-ml injections of 0.2% ropivacaine and 0.5 mg epinephrine to the surgical region. In group S, participants received SNB with 20 ml of 0.375% ropivacaine. After TKA, Numeric Rating Scale (NRS) scores for the first 24 h post-operation were compared via repeated-measures analysis of variance (ANOVA) as the primary outcome. Other outcome measures included NRS score changes within groups, area under the curve for the NRS scores, total analgesic dose, change in knee flexion and extension, pain control satisfaction, nausea and vomiting, and hospital stay duration. RESULTS: NRS score changes were greater in group L than in group S (P < 0.01, ANOVA) and greater in group L than in group S at three postoperative time points: 3 h (P < 0.01), 6 h (P < 0.01), and 12 h (P = 0.013; Mann-Whitney U test). Changes in the mean NRS score were observed in each group (P < 0.01, Friedman test). No significant differences were detected in the other outcome measures (Mann-Whitney U, Wilcoxon signed-rank, and chi-squared tests). CONCLUSIONS: Sciatic nerve block with femoral nerve block is superior to local anesthetic infiltration with femoral nerve block for postoperative pain control within 3-12 h of total knee arthroplasty. TRIAL REGISTRATION: UMIN-CTR ID: 000013364 R: 000015591.

Comparison of local infiltration of analgesia and sciatic nerve block in addition to femoral nerve block for total knee arthroplasty.

We conducted a prospective randomized controlled trial to test the null hypothesis that there is no difference between sciatic nerve block (SNB) and local infiltration of analgesia (LIA) regarding postoperative analgesia after total knee arthroplasty (TKA), when administrated in addition to femoral nerve block (FNB). Forty-six patients scheduled for TKA were randomized into two groups: concomitant administration of FNB and SNB or FNB and LIA. Average pain scores during the first 21days after surgery were similar in the two groups and remained at low level. There was no significant difference in the need for adjuvant analgesics, patient satisfaction level, the time to achieve rehabilitation goals, and length of hospital stay. The LIA offers a potentially safer alternative to SNB as an adjunct to FNB.

Late Onset of the Fabella Syndrome after Total Knee Arthroplasty.

Some differential diagnosis is thought due to knee pain after total knee arthroplasty (TKA) and fabella syndrome may cause post-TKA pain due to mechanical irritation. In this present case, a 64-year-old woman experienced lateral knee pain which was localized at the iliotibial ligament 8 years after the surgery. Fabella syndrome was diagnosed, and fabellectomy provided immediate resolution of the pain. The previous reports have revealed the symptoms occurred after 6 days to a year after total knee arthroplasty. This case widens the time span and the consideration of the fabella syndrome. The reason of this late onset symptom could be due to the enlargement of the fabella over time. We report that the differential diagnosis of fabella syndrome should be thought in symptoms of late onset knee pain after total knee arthroplasty.

Detection of calcium pyrophosphate dihydrate crystals in knee meniscus by dual-energy computed tomography.

BACKGROUND: Calcium pyrophosphate dihydrate (CPPD) crystals are commonly observed in osteoarthritic joints. The aim of our study was to investigate the efficacy of a dual-energy computed tomography (DECT) for detecting CPPD crystals in knee meniscus. METHODS: Twenty-six patients undergoing primary total knee arthroplasty were included in the study. Radiographs of knee joint and synovial fluid specimens were analyzed for the presence of CPPD crystals. Meniscus extracted during surgery was scanned using DECT. Sensitivity and specificity of DECT and radiograph for detecting CPPD crystals were calculated against a reference standard (polarizing light microscopy of synovial fluid aspirate). Meniscus in which CPPD crystals were suspected with DECT was further examined to confirm the crystals using a polarized microscopy. RESULTS: CPPD crystals in synovial fluid were observed in 9 (36%) patients. The sensitivity and specificity of DECT in the detection of CPPD crystals, against microscopic identification, were 77.8 and 93.8%, respectively. The sensitivity and specificity of conventional radiography in the detection of CPPD crystals were 44.4 and 100%, respectively. DECT was able to detect the area where CPPD crystals were deposited in the meniscus. CONCLUSION: DECT provides good diagnostic sensitivity and specificity for detection of CPPD crystals in knee meniscus as well as spatial information about CPPD crystals. DECT is currently a research tool, but we believe that DECT can be a useful instrument to diagnose CPPD deposition disease, especially for the regions where aspiration is difficult to be performed such as pubic symphysis, atlantoaxial joint, interphalangeal joint.

Local infiltration of analgesia and sciatic nerve block provide similar pain relief after total knee arthroplasty.

BACKGROUND: Although femoral nerve block provides satisfactory analgesia after total knee arthroplasty (TKA), residual posterior knee pain may decrease patient satisfaction. We conducted a randomized controlled trial to clarify the efficacy of the sciatic nerve block (SNB) and local infiltration of analgesia with steroid (LIA) regarding postoperative analgesia after TKA, when administrated in addition to femoral nerve block (FNB). METHODS: Seventy-eight patients were randomly allocated to the two groups: concomitant administration of FNB and SNB or FNB and LIA. The outcome measures included post-operative pain, passive knee motion, C-reactive protein level, time to achieve rehabilitation goals, the Knee Society Score at the time of discharge, patient satisfaction level with anesthesia, length of hospital stay, surgical time, and complications related to local anesthesia. RESULTS: The patients in group SNB showed less pain than group LIA only on postoperative hours 0 and 3. Satisfactory postoperative analgesia after TKA was also achieved with LIA combined with FNB, while averting the risks associated with SNB. The influence on progress of rehabilitation and length of hospital stay was similar for both anesthesia techniques. CONCLUSIONS: The LIA offers a potentially safer alternative to SNB as an adjunct to FNB, particularly for patients who have risk factors for sciatic nerve injury.