Role of tear size and tendon degeneration for development of pain in rat models of rotator cuff tear.

BACKGROUND: Rotator cuff tear (RCT) is a frequent etiology of shoulder pain and disability; however, the triggers for the onset and aggravation of pain remain obscure. In this study, we established novel rat RCT models to examine the impact of tear size and tendon degeneration on pain. METHODS: Fifty-five adult male Sprague-Dawley rats were allocated into 4 study groups: large tear (L group, n = 10), small tear (S group, n = 15), small tear with scratching (S+ group n = 15), and sham surgery (Sham group, n = 15). Pain-related behaviors were evaluated by weight distribution of forelimbs during a 5-minute free gait using a dynamic weight-bearing apparatus at 2, 4, 6, and 8 weeks. Calcitonin gene-related peptide (CGRP) expressions in ipsilateral dorsal root ganglion (DRG) neurons of C4, C5, and C6 were evaluated at 4 and 8 weeks. The area of scar tissues around the torn tendon, infiltration of inflammatory cells, and severity of tendon degeneration (modified Bonar score) were histologically assessed at 4 and 8 weeks. Additionally, enzyme-linked immunosorbent assay (ELISA) was conducted to evaluate the levels of cyclooxygenase-2 (COX-2) and nerve growth factor (NGF) expression in torn tendons and surrounding tissues at 4 weeks. RESULTS: The weight distribution ratio (ipsilateral and contralateral side) was significantly decreased in the L and S+ group compared with its baseline and Sham group (P < .05), but the S group showed no significant difference compared with the Sham. The ratio of CGRP-immunoreactive neurons in the DRGs was significantly higher in the L and S+ groups than in the S and Sham groups. The histologic assessment indicated that scar tissue formation was more extensive in the L group than in the S and S+ groups. Still, there was no significant difference between the S and S+ groups. The modified Bonar score was considerably higher in the S+ group than in the S group. Furthermore, ELISA analysis demonstrated no significant disparity in COX-2 levels between the groups; however, NGF levels were substantially higher in the S+ group than in the S and Sham groups. CONCLUSION: The present study provides compelling evidence that large RCT is strongly associated with heightened pain severity in a rat model. Nevertheless, even a small tear can significantly aggravate pain when the torn tendon is degenerated. CGRP upregulation driven by peripheral NGF possibly played a pivotal role in the genesis and exacerbation of pain in small RCT.

Association between infrapatellar fat pad ultrasound elasticity and anterior knee pain in patients with knee osteoarthritis.

This study investigates whether infrapatellar fat pad (IPFP) elasticity is associated with anterior knee pain in patients with knee osteoarthritis (KOA). The IPFP elasticity of 97 patients with KOA (Kellgren and Lawrence [KL] grades of the femorotibial and patellofemoral joints ≥ 2 and ≤ 2, respectively), aged 46-86 years, was evaluated via shear wave speed using ultrasound elastography. The patients were divided into two groups according to the presence or absence of anterior knee pain. Univariate analyses were used to compare patient age, sex, femorotibial KL grade, magnetic resonance imaging findings (Hoffa, effusion synovitis, bone marrow lesion scores, and IPFP size), and IPFP elasticity between the groups. Multivariate logistic regression analyses were subsequently performed using selected explanatory variables. IPFP elasticity was found to be associated with anterior knee pain in the univariate (p = 0.007) and multivariate (odds ratio: 61.12, 95% CI 1.95-1920.66; p = 0.019) analyses. Anterior knee pain is strongly associated with stiffer IPFPs regardless of the femorotibial KL grade, suggesting that ultrasound elastography is useful for the diagnosis of painful IPFP in patients with KOA.

Associations of serum leptin levels with intra-articular inflammatory cytokine levels in acute arthritic and nonarthritic knees of mice.

BACKGROUND: The roles of serum leptin in knee joint inflammation are unclear. The objective of this study was to identify any associations of serum leptin level with intra-articular inflammatory cytokine levels in acute arthritic and nonarthritic knees of mice. METHODS: Acute arthritis was induced by intra-articular injection of 2% carrageenan. Three groups (leptin-deficient ob/ob, wild-type (WT) and high-fat diet (HFD)-fed WT) were made. Serum leptin and inflammatory cytokines in the infrapatellar fat pad and synovium were measured before and 24 hr after injection. Affected knee joints were excised for histology 24 hr after injection. RESULTS: The HFD-WT group had significantly higher serum leptin than the ob/ob and WT groups before and after carrageenan injection. The HFD-WT group had significantly higher IL-1? and IL-6 in the infrapatellar fat pad and synovium than ob/ob and WT before injection but significantly lower IL-1?, IL-6 and TNF-? than the ob/ob group at 24 hr. CONCLUSIONS: Hyperleptinemia induced by a HFD is involved in low-grade intra-articular inflammation in nonarthritic knee joints. In contrast, leptin deficiency causes excessive intra-articular inflammation in carrageenan-induced acute arthritis. Leptin alleviates acute arthritis, while chronic hyperleptinemia is involved in low-grade inflammation in normal knee joints. J. Med. Invest. 70 : 54-59, February, 2023.

A Novel Rat Model to Study Postsurgical Pain After Joint Replacement Surgery.

Purpose: The mechanisms underlying chronic postsurgical pain after joint replacement (JR) are complex, and it has been suggested that chronic postsurgical pain can develop as a result of inadequate acute pain management. Few studies have addressed acute pain after JR using specific animal models. This study aimed to develop a novel JR model focused on postsurgical pain assessment and the time course of pain recovery. Materials and Methods: Rats were allocated to the following three groups: sham (joint exposure), joint destruction (JD; resection of the femoral head), and JR (femoral head replacement using an originally developed implant). The time course of postsurgical pain behavior was measured using a dynamic weight-bearing apparatus, along with radiological assessments. The expression of calcitonin gene-related peptide-immunoreactive (CGRP-IR) neurons in the dorsal root ganglion (DRG) was evaluated by immunohistochemistry on days 28 and 42. Results: The ratio of weight-bearing distribution in the JR group gradually recovered from day 14 and reached the same level as that in the sham group on day 42, which was significantly greater than that in the JD group after day 7 (p<0.05). Radiologically, no significant issues were found, except for transient central migration of the implant in the JR group. The percentage of CGRP-IR DRG neurons in the JR group was significantly lower than that in the JD group on day 28 (mean, 37.4 vs 58.1%, p<0.05) and day 42 (mean, 32.3 vs 50.0%, p<0.05). Conclusion: Our novel JR model presented acute postsurgical pain behavior that was successfully recovered to the baseline level at day 42 after surgery. Difference of the pain manifestation between the JR and JD groups could be supported by the expression of CGRP-IR in DRG neurons. This model is the first step toward understanding detailed mechanisms of post-JR pain.

Increased Calcitonin Gene-Related Peptide Expression in DRG and Nerve Fibers Proliferation Caused by Nonunion Fracture in Rats.

PURPOSE: Nonunion bone fracture can be a cause of persistent pain, but the pathophysiology remains largely unknown. The objective of this study was to identify how nonunion affect persistent pain after fracture. Specifically, we evaluated the association of neuropeptide change in dorsal root ganglia (DRG) and nerve proliferation at fracture sites with pain. METHODS: Rat union and nonunion fracture models were created. A piece of latex glove was placed at the fracture site to create a nonunion model. At 6 weeks after surgery, bone healing was assessed using radiography. In addition, the presence of calcitonin gene-related peptide-immunoreactive (CGRP-IR) DRG at the level of L3 and anti-growth associated protein 43-immunoreactive (GAP43-IR) nerve fibers in the scar tissue between the bone fragments were evaluated. Pain-related behavior was assessed using forced treadmill running. RESULTS: In radiological images at 6 weeks after surgery, callus formation was formed continuously between bone fragments in the union models. On the one hand, a clear gap was detected between fragments in nonunion models. The percentage of CGRP-IR DRG cells and the density of GAP43-IR nerve fibers in the scar tissue between the bone fragments in nonunion models was significantly higher than that in union models (p < 0.05). An increase in inflammatory cell infiltrate was observed in scar tissues in the nonunion models. During forced treadmill running, rats in the union model could run significantly longer than those in the nonunion models. CONCLUSION: Increased CGRP expression in DRG cells and abnormal nerve proliferation secondary to prolonged inflammation could lead to persistent pain after bone fracture. In clinical practice, early achievement of bone union may minimize the development of persistent pain after fractures.

Efficacy and safety of magnetic resonance-guided focused ultrasound treatment for refractory chronic pain of medial knee osteoarthritis.

OBJECTIVE: To elucidate the efficacy and safety of MRgFUS in the treatment for refractory pain derived from medial knee OA. METHODS: Twenty patients with medial knee OA eligible for total knee arthroplasty were included in this prospective, non-controlled study (UMIN000010193). MRgFUS treatment was provided at the site of most severe tenderness around the medial femorotibial joint of each patient under real-time monitoring of temperature. The goal temperature of the targeted bone surface was 55 °C. Numerical rating scale (NRS) worst pain scores, Western Ontario and McMaster Universities osteoarthritis index (WOMAC) scores, EuroQol 5 dimensions index (EQ-5D) scores and pressure pain threshold (PPT) were evaluated before treatment (baseline) and at 1 week and 1, 3, 6, and 12 months post-treatment, respectively. Complications and adverse events were also assessed clinically and radiographically. RESULTS: Treatment response (a 50% or greater decrease in NRS score) was seen in 14 patients (14/19, 73.7%) at 12 months post-treatment. Mean NRS score rapidly decreased at 1 month after treatment and continued to decline through the following 12 months. At final follow-up, mean NRS score was 3.2 ± 1.9, significantly lower than at baseline (p = 0.0013). Mean WOMAC and EQ-5D scores also improved significantly from 1 month after treatment. Fifteen patients showed significant sustained increases in PPTs at the sites of most severe tenderness. No serious adverse events were observed during and after treatment. CONCLUSIONS: MRgFUS treatments were effective not only for managing refractory pain, but also for improving physical functions without adverse events in elderly patients with medial knee OA.

Bone marrow derived mast cells injected into the osteoarthritic knee joints of mice induced by sodium monoiodoacetate enhanced spontaneous pain through activation of PAR2 and action of extracellular ATP.

Conditions that resemble osteoarthritis (OA) were produced by injection of sodium monoiodoacetate (MIA) into the knee joints of mice. Bone marrow derived mast cells (BMMCs) injected into the OA knee joints enhanced spontaneous pain. Since no spontaneous pain was observed when BMMCs were injected into the knee joints of control mice that had not been treated with MIA, BMMCs should be activated within the OA knee joints and release some pain-inducible factors. Protease activated receptor-2 (PAR2) antagonist (FSLLRY-NH2) almost abolished the pain-enhancing effects of BMMCs injected into the OA knee joints, suggesting that tryptase, a mast cell protease that is capable of activating PAR2, should be released from the injected BMMCs and enhance pain through activation of PAR2. When PAR2 agonist (SLIGKV-NH2) instead of BMMCs was injected into the OA knee joints, it was also enhanced pain. Apyrase, an ATP degrading enzyme, injected into the OA knee joints before BMMCs suppressed the pain enhanced by BMMCs. We showed that purinoceptors (P2X4 and P2X7) were expressed in BMMCs and that extracellular ATP stimulated the release of tryptase from BMMCs. These observations suggest that ATP may stimulate degranulation of BMMCs and thereby enhanced pain. BMMCs injected into the OA knee joints stimulated expression of IL-1ß, IL-6, TNF-α, CCL2, and MMP9 genes in the infrapatellar fat pads, and PAR2 antagonist suppressed the stimulatory effects of BMMCs. Our study suggests that intermittent pain frequently observed in OA knee joints may be due, at least partly, to mast cells through activation of PAR2 and action of ATP, and that intraarticular injection of BMMCs into the OA knee joints may provide a useful experimental system for investigating molecular mechanisms by which pain is induced in OA knee joints.

Chronic postsurgical pain after total knee arthroplasty: A prospective cohort study in Japanese population.

OBJECTIVES: To elucidate the prevalence and risk factors of chronic postsurgical pain (CPSP) after primary total knee arthroplasty (TKA) in Japanese population. METHODS: Consecutive patients undergoing primary TKA in a Japanese tertiary hospital (211 knees) were assessed. CPSP after TKA was defined as moderate to severe pain (VAS >30 mm), either at rest or during walking, one year after surgery. Clinical and radiographic data were compared between CPSP and non-CPSP groups and multivariate logistic regression was used to identify predictors of CPSP. RESULTS: The prevalence of CPSP was 8.8%. CPSP group showed significantly higher preoperative WOMAC subscales (pain, function and stiffness), higher rate of postoperative coronal malalignment (femorotibial angle >178° or <170°) and larger varus angle of tibial component compared with non-CPSP group. Logistic regression analysis revealed that preoperative higher WOMAC pain and postoperative coronal malalignment were independent risk factors of CPSP. In a subgroup analysis of patients with well-aligned TKA, preoperative pain VAS at rest was the only risk factor of CPSP. CONCLUSION: Preoperative severe pain and postoperative coronal malalignment were independent risk factors of CPSP after TKA. Preoperative pain management in patients with severe pain and good coronal alignment after TKA possibly minimize the development of CPSP.

Accuracy of acetabular cup placement using an angle-adjusting alignment guide with laser pointer in total hip arthroplasty.

PURPOSE: To evaluate cup-positioning accuracy in total hip arthroplasty (THA) using a novel angle-adjusting alignment guide with laser pointer and determine whether level of surgical experience affects accuracy of cup placement or not. METHODS: We included 117 hips in 104 patients who underwent THA using the novel guide. We retrospectively reviewed 44 hips in 40 patients who underwent THA before the novel guide was introduced. We compared differences in cup angles between the novel guide group and the conventional guide group as well as the discrepancies in targeted angles between the experienced surgeon group and the inexperienced surgeon group. RESULTS: There were 114/117 hips (97.4%) within the Lewinnek safe zone in the novel guide group and 32/44 hips (72.7%) within the safe zone in the conventional guide group. There were significantly fewer outliers in the novel guide group (p < 0.001). In the experienced surgeon group, the mean absolute errors in inclination and anteversion were 2.0 ± 1.7° and 2.1 ± 2.3°, respectively; which were not significantly different from those in the inexperienced surgeon group (2.3 ± 2.1° and 2.8 ± 2.3°, respectively). CONCLUSION: The novel angle-adjusting alignment guide with laser pointer is a simple tool that provides better accuracy of cup position than that obtained using conventional guides. Accurate cup placement is possible using the novel guide, regardless of surgeons' experience.

Effects of MRgFUS Treatment on Musculoskeletal Pain: Comparison between Bone Metastasis and Chronic Knee/Lumbar Osteoarthritis.

Local bone denervation by magnetic resonance-guided focused ultrasound (MRgFUS) is a promising tool for alleviation of pain in patients with painful bone metastasis (BM). Considering the underlying mechanism of pain alleviation, MRgFUS might be effective for various bone and joint diseases associated with local tenderness. This study was conducted to clarify the therapeutic effect of focused ultrasound in patients with various painful bone and joint diseases that are associated with local tenderness. Ten patients with BM, 11 patients with lumbar facet joint osteoarthritis (L-OA), and 19 patients with knee osteoarthritis (K-OA) were included. MRgFUS treatment was applied to the bone surface with real-time temperature monitoring at the target sites. Pain intensity was assessed using a 100 mm numerical rating scale (NRS) at various time points. Pressure pain threshold (PPT) was evaluated on the sonication area and control sites. Compared to baseline, the pain NRS scores significantly decreased in all groups 1 month after treatment, and PPT at the treated sites significantly increased in all groups 3 months after treatment. The percentage of patients who showed a ≥ 50% decrease in pain NRS scores at 1 month after treatment was 80% in BM, 64% in L-OA, and 78% in K-OA groups. PPTs were significantly higher after treatment at all evaluation time points. This study indicated that MRgFUS is effective in reducing pressure pain at the site of most severe tenderness in patients with painful bone and joint diseases. Treatment response was comparable between patients with BM, L-OA, and K-OA.

Additional benefit of local infiltration of analgesia to femoral nerve block in total knee arthroplasty: double-blind randomized control study.

PURPOSE: Multimodal analgesia has become an important concept in current pain management following total knee arthroplasty (TKA). However, controversy remains over what is the most accepted combination. In this study, the additional benefits of local infiltration of analgesia to femoral nerve block were evaluated. METHODS: Forty patients were randomly allocated into a combined local infiltration of analgesia and femoral nerve block or femoral nerve block alone group. In the former, analgesic drugs consisting of ropivacaine and dexamethasone were injected into the peri-articular tissues, while the same amount of saline was injected into the femoral nerve block group. The primary outcome measure was the total amount of fentanyl consumption by the patient-controlled analgesia pump during the 48-h post-operative period. RESULTS: A combination of local infiltration of analgesia and femoral nerve block had less total fentanyl consumption and a larger knee ROM at post-operative day 2 than femoral nerve block alone (p < 0.05). C-reactive protein levels in the combined treatment group were significantly lower than the femoral nerve block group at post-operative day 3 (p < 0.01). There was no difference between the two groups, post-operatively, on the visual analogue scale for pain at rest or while walking, quadriceps strength, timed up and go test, circumference of thigh, Knee Society Score, and Western Ontario and McMaster Universities Osteoarthritis Index. CONCLUSION: The addition of local infiltration of analgesia to femoral nerve block promoted post-operative pain relief and the recovery of knee ROM in the early post-operative period. This combination is an effective method for post-operative pain management after TKA. LEVEL OF EVIDENCE: Randomized controlled trial, Level I.

Chronological changes in functional cup position at 10 years after total hip arthroplasty.

PURPOSE: This study aims to clarify the chronological changes in functional cup position at a minimum follow-up of 10 years after total hip arthroplasty (THA), and to identify the risk factors influencing a significant difference in functional cup position during the postoperative follow-up period. METHODS: We evaluated the chronological changes in functional cup position at a minimum follow-up of 10 years after THA in 58 patients with unilateral hip osteoarthritis. Radiographic cup position was measured on anteroposterior pelvic radiographs with the patient in the supine position, whereas functional cup position was recorded in the standing position. Radiographs were obtained before, 3 weeks after, and every 1 year after surgery. RESULTS: Functional cup anteversion (F-Ant) increased over time, and was found to have significantly increased at final follow-up compared to that at 3 weeks after surgery (p<0.01). The maximum postoperative change in F-Ant was 17.0° anteriorly; 12 cases (21%) showed a postoperative change in F-Ant by >10° anteriorly. Preoperative posterior pelvic tilt in the standing position and vertebral fractures after THA were significant predictors of increasing functional cup anteversion. CONCLUSIONS: Although chronological changes in functional cup position do occur after THA, their magnitude is relatively low. However, posterior impingement is likely to occur, which may cause edge loading, wear of the polyethylene liner, and anterior dislocation of the hip. We believe that, for the combined anteversion technique, the safe zone should probably be 5°-10° narrower in patients predicted to show considerable changes in functional cup position compared with standard cases.

Less deep vein thrombosis due to transcutaneous fibular nerve stimulation in total knee arthroplasty: a randomized controlled trial.

PURPOSE: It has been known for years that deep vein thrombi (DVT) start to develop during total joint arthroplasty. Previously, we reported effective prevention of venous stasis by transcutaneous electrical nerve stimulation (TENS). It is hypothesized that TENS might be a thromboprophylactic tool for the limb undergoing surgery. The purpose of this study is to clarify the clinical efficacy and safety of TENS in patients during total knee arthroplasty (TKA). METHODS: Ninety patients undergoing primary TKA were involved and randomly allocated to the TENS or control group. In the TENS group, electrical stimulation of the common fibular nerve, which produced a brisk dorsiflexion of the ankle, was performed for the operated leg during surgery. In the control group, no electrical stimulation was applied. Serum D-dimer and soluble fibrin monomer complex (SFMC) levels were measured before surgery, immediately after surgery, and post-operative day (POD) 1. Ultrasonography was performed on POD 1. RESULTS: Immediately after surgery, D-dimer and SFMC levels of each group were significantly lower in the TENS group compared with control (p < 0.05). The incidence of DVT was 11 % (five cases) in the TENS group while 31 % (14 cases) in control (p = 0.02). There were no adverse effects related to TENS. CONCLUSIONS: TENS during TKA showed significant effects on preventing DVT. Sustaining muscle pump activation during surgery prevented not only venous stasis, but also hypercoagulability of blood. Intraoperative TENS is a safe and novel strategy against early post-operative thromboembolism, which is difficult to be completed through existing prophylaxis after total joint arthroplasty. LEVEL OF EVIDENCE: Randomized controlled trial, Level I.

Less invasive modified Spitzy shelf procedure for patients with dysplasia of the hip.

The shelf procedure for developmental dysplasia of the hip (DDH) is a simpler technique compared with periarticular acetabular osteotomies. However, the most commonly used approach involves the exposure of a large section of the outer iliac surface via a long skin incision and is relatively invasive. We have developed a mini one-incision technique for shelf procedure using bioabsorbable material, based on a modified Spitzy method. In the present report, we describe this procedure and outcomes. For the procedure, the patients are positioned in the lateral position and a 6-8-cm skin incision is made. The interval between the gluteus medius and the tensor fascia lata is developed without any muscle splitting. Thereafter, image intensification is used for accurate positioning of a slot for the new shelf, and a bone graft for the new shelf is obtained from the internal cortex of the iliac wing. The patient is then positioned with the hip in flexion; through the same sliding skin incision, the bone graft is impacted into the slot, and bioabsorbable screws or plates are implanted to cover and stabilise the new shelf. Cancellous bone chips are packed into the triangular space surrounded by the outer iliac surface, the new shelf, and the bioabsorbable screws or plate. We performed this procedure in 9 patients (12 hips). No progression of osteoarthritis was observed during the follow-up period (mean 28 months). The advantages of this procedure include the small, single, skin incision and minimal removal of the gluteus medius from the outer iliac surface. Based on our results, we believe that this procedure could be effective for the treatment of DDH.

The dorsal pedis artery as a new distal landmark for extramedullary tibial alignment in total knee arthroplasty.

PURPOSE: It is better to use multiple anatomical landmarks to reduce errors in component alignment in total knee arthroplasty. Therefore, it is worthwhile to find a new landmark that can be used as an addition to conventional ones. Herein, we assessed the dorsal pedis artery as a new distal landmark for extramedullary tibial alignment. METHODS: Fifty-two ankles in patients undergoing total knee arthroplasty and 10 ankles in normal controls were included. Color Doppler ultrasonography was used to locate the dorsal pedis artery at the level of the ankle joint. Conventional landmarks, including the tibialis anterior tendon, the extensor hallucis longus tendon, the extensor digitorum longus tendon, and the malleolar centre, were also located on ultrasound images. The distances between the ankle centre and each landmark were measured and compared. RESULTS: The dorsal pedis artery was absent in 2 patients and impalpable but visible with ultrasonography in other 2 patients. The dorsal pedis artery was located anatomically closest to the ankle centre in patients (0.4 ± 3.4 mm lateral). Statistical analysis showed that the dorsal pedis artery, the extensor hallucis longus tendon, and the malleolar centre were located significantly closer to the ankle centre comparing with the extensor digitorum longus tendon and the tibialis anterior tendon in both patients and controls (p < 0.001). CONCLUSIONS: As long as the dorsal pedis artery exists, it can be used as an addition to the conventional landmarks in total knee arthroplasty. Using this new landmark will help reduce errors in coronal plane alignment of tibial component. LEVEL OF EVIDENCE: II.

Effects of dexamethasone on local infiltration analgesia in total knee arthroplasty: a randomized controlled trial.

PURPOSE: Intraoperative local infiltration analgesia has gained increasing popularity in joint replacement surgery. Because there is considerable variation among drug combinations, analgesic effects of each drug are not well understood. The purpose of this study was to clarify the efficacy of the addition of steroid to local anaesthetics in local infiltration analgesia during total knee arthroplasty. METHODS: Forty patients were randomly allocated to the steroid or control group. Patients in the steroid group received peri-articular injection of ropivacaine, dexamethasone and isepamicin, while dexamethasone was omitted from the analgesic mixture in the control group. Primary outcome was pain severity at rest using 100 mm visual analogue scale. RESULTS: Pain severity in the steroid group was lower than control group and there were significant differences between groups at post-operative day 1 and 3. Reduction in post-operative pain was associated with a decrease in serum C-reactive protein and interleukin 6 in drainage fluid. The number of patients who were able to perform straight leg raise within post-operative day 2 was 15/20 in the steroid group, which was significantly higher than the control group 5/20. CONCLUSION: Adding steroid to local anaesthetics in local infiltration analgesia reduced inflammation both locally and systemically, resulting in significant early pain relief and rapid recovery in total knee arthroplasty.

MR-guided focused ultrasound for the novel and innovative management of osteoarthritic knee pain.

BACKGROUND: Severe knee pain associated with osteoarthritis (OA) is one of the most common and troublesome symptoms in the elderly. Recently, local bone denervation by MR-guided focused ultrasound (MRgFUS) has been demonstrated as a promising tool for pain palliation of bone metastases. The purpose of this study was to develop a novel treatment for knee OA using MRgFUS, and to validate its safety and efficacy. METHODS: Eight patients with medial knee pain and eligible for total knee arthroplasty were included. MR-guided focused sonication treatments were applied to bone surface just below the rim osteophyte of medial tibia plateau with real-time monitoring of the temperature in the target sites. The pain intensity during walking was assessed on a 100 mm visual analog scale (VAS) before and after treatment. Pressure pain thresholds (PPTs) were also evaluated over several test sites adjacent to the sonication area and control sites one month after treatment. RESULTS: Six patients (75%) showed immediate pain alleviation after treatment, and four of them demonstrated long-lasting effect at 6-month follow up (mean VAS reduction; 72.6%). In responders, PPTs in medial knee were significantly increased after treatment (Median; pre- 358 kpa vs post- 534 kpa, p < 0.0001). There were no adverse side effects or complications during and after treatment. CONCLUSIONS: These initial results illustrate the safety and efficacy of the newly developing MRgFUS treatment. Significant increase of PPTs on treated area showed successful denervation effect on the nociceptive nerve terminals. MRgFUS is a promising and innovative procedure for noninvasive pain management of knee OA. TRIAL REGISTRATION: Trial Registration: UMIN000010193.

Local infusion analgesia using intra-articular double lumen catheter after total knee arthroplasty: a double blinded randomized control study.

PURPOSE: Although intra-operative local infiltration analgesia has gained increasing popularity in joint replacement surgery, it is not clear whether postoperative local infusion analgesia using an indwelling catheter provides clinically important additional effects. We, therefore, conducted a randomized controlled trial to clarify the efficacy of the originally developed local infusion analgesia technique in total knee arthroplasty. METHODS: Forty patients were randomly allocated to the local infusion analgesia or control group. Patients in the local infusion analgesia group received intermittent bolus intra-articular injection of analgesics consisting of ropivacaine, dexamethasone, and isepamicin until postoperative 48 h. Primary outcome was pain severity at rest using 100-mm visual analogue scale. RESULTS: Pain severity in patients of the local infusion analgesia group was lower than control group, and there were significant differences between groups at POD1 (p = 0.025) and POD3 (p = 0.007). Reduction of postoperative pain was associated with a decrease in C-reactive protein level and earlier achievement of straight leg raise. In addition, postoperative drain volume was reduced in the local infusion analgesia group. CONCLUSION: Although larger studies are needed to examine its safety, the local infusion analgesia alone provided clinically significant analgesic effects and rapid recovery in total knee arthroplasty.

Septic arthritis of the knee associated with calf abscess.

Septic arthritis associated with extra-articular abscess is rare. We report on 2 non-rheumatic patients with septic arthritis of the knee associated with calf abscess. Magnetic resonance imaging showed a distinct leakage pathway from the knee joint in each patient. One was a ruptured popliteal cyst (posteromedial). Another was a pathologic popliteus hiatus (posterolateral). These patients underwent open drainage of the calf abscess via a small incision, followed by arthroscopic debridement of the knee. Careful palpation of the lower leg, followed by magnetic resonance imaging and needle aspiration, is important to exclude a possible extra-articular abscess regardless of the presence of a popliteal cyst.