Arthroscopic labral repair combined with less invasive open-shelf acetabuloplasty for patients with developmental dysplasia of the hip.

Hip arthroscopy has become widely used for intra-articular lesions, such as labral tears and femoral acetabular impingement. However, its use in patients with developmental dysplasia of the hip (DDH) has been controversial and has historically demonstrated mixed results, as acetabular dysplasia may cause instability due to insufficient bony coverage of the femoral head, thus causing excessive stress on the repaired labrum and cartilage. We devised a combined hip arthroscopic labral repair and a less invasive open-shelf procedure using a small skin incision as an anterolateral portal in hip arthroscopy. This novel procedure may improve the stability of the repaired labrum with a bony covering in a minimally invasive manner. Moreover, the shelf procedure can be performed under direct vision in a comparatively safe and precise manner. In total, 13 hips with DDH underwent the procedure for labral tears. All patients were females, with a mean age of 30 years. The mean follow-up period was 33 months. The mean Harris hip score improved from 74.2 to 93.6, and Oxford Hip score improved from 32.4 to 19.3. According to the Tönnis classification, the grade of arthritis preoperatively was grade 0 for nine hips and grade I for four hips. No radiographic progression of osteoarthritis was observed. It is possible that this novel procedure could be an effective treatment for labral tears with DDH and may prevent the early onset of secondary osteoarthritis. In this technical tip, we describe hip arthroscopic labral repair combined with a less invasive open-shelf acetabuloplasty in further detail.

Prevalence of iliopsoas bursitis in patients with end-stage hip osteoarthritis.

OBJECTIVES: Iliopsoas bursitis (IB) is a relatively rare condition that is associated with hip diseases. It can cause neurological symptoms and swelling of the lower extremities by compressing the femoral nerve and vessels. The aim of this study is to examine the prevalence of IB in patients with end-stage hip osteoarthritis. METHODS: A total of 544 patients underwent total hip arthroplasty between May 2010 and May 2019. All patients were examined using computed tomography (CT) to perform preoperative planning. We reviewed the CT images and examined the prevalence and size of IB. These lesions were divided into three types based on their shape (round type, oval type, and heart-shaped type). RESULTS: Of the 544 patients, IB was found in 37 patients. We observed the round type in 4 patients, the oval type in 31 patients, and the heart-shaped type in 2 patients. Two patients showed severe swelling in the legs and had a blood circulatory disorder of the legs. Both cases were heart-shaped bursitis. CONCLUSION: Symptomatic IB was observed in two cases, both of which had a heart shape surrounding the iliopsoas tendon and femoral neurovascular bundle. Although symptomatic IB is a rare condition, special attention is required for heart-shaped IB.

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.

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.

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.

A novel mice model of acute flares in osteoarthritis elicited by intra-articular injection of cultured mast cells.

PURPOSE: Mast cells are multifunctional in osteoarthritis (OA), and infiltration of activated mast cells likely contributes to disease severity and progression. However, the detailed mechanisms of action are unclear. The purpose of this study was to elucidate the role of mast cell infiltration in OA at histological level using a new mice model and to investigate pharmacological inhibitory effects of existing mast cell stabilizers in this model. METHODS: Mice were injected intra-articularly with monosodium iodoacetate (MIA 0.5 mg) or PBS on day 0, and PBS, with or without mast cells (MC: 1 × 106 cells) on day 14. They were divided into four groups: OA flare (MIA + MC), OA (MIA + PBS), MC non-OA (PBS + MC), and PBS non-OA (PBS + PBS). In OA flare, the MC stabilizer drug (tranilast: 400 mg/kg/day) or PBS was administered intraperitoneally from days 15 to 21. RESULTS: Histologically, modified Mankin score of the OA flare was significantly higher than that of OA (7.0 [1.8] vs. 3.3 [1.3], P < 0.05), and a larger number of mast cells was observed in OA flare than in OA (34.5 [6.3]/mm2 vs. 27.2 [2.3]/mm2, P < 0.05) on day 22. OA flare also showed acute exacerbation of pain and increased gene expression of pro-inflammatory cytokines and aggrecanase compared with OA. Administration of tranilast to OA flare-up provoked significant improvements in term of histological changes, pain, and gene expression at day 22. CONCLUSION: Our novel model possibly mimics OA flare conditions, which may open a new strategy of disease-modifying treatment for OA, focused on controlling the multiple functions of mast cells.

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.