The infraspinatus muscle activity during pitching motion in baseball players with shoulder instability.

BACKGROUND: Shoulder microinstability is often overlooked, which can be problematic, especially in overhead athletes. The slipping phenomenon is defined as posterior or lateral sliding of the humeral head in an elevated arm. When the shoulder is close to the end range of stability, the infraspinatus is highly activated and keeps the shoulder in the glenoid cavity. This study aimed to examine the characteristic physical function and infraspinatus activity during the pitching motion in baseball pitchers with shoulder instability. METHODS: Twenty-one male baseball pitchers participated and were divided into 2 groups based on radiograph findings at zero position: slipped (group S) and nonslipped (group N) groups. Physical function using Hara test and infraspinatus muscle activity during pitching were evaluated. RESULTS: The infraspinatus muscle activity during the acceleration phase was significantly greater in group S (59.5 ± 33.0%MVC) than in group N (33.0 ± 16.9%MVC) (P < .05). Positive rate of the Hara test in group S was significantly high in the loose test and elbow push test. CONCLUSIONS: This study shows that baseball pitchers with slipping phenomenon have capsular laxity and scapular instability that indicate high infraspinatus muscle activity during the acceleration phase. Therefore, repetitive pitching with hyperactivity of the infraspinatus on the slipping shoulder may cause fatigue and dysfunction.

Stromal cell-derived factor 1 (SDF-1, CXCL12) is increased in subacromial bursitis and downregulated by steroid and nonsteroidal anti-inflammatory agents.

Several studies have demonstrated that inflammation in the subacromial bursa is an important component in the pathogenesis of impingement syndrome. We have demonstrated in a previous study that many inflammatory cytokines, including stromal cell-derived factor 1 (SDF-1, CXCL12), are increased in the subacromial bursa [Blaine et al. 2005. J Shoulder Elbow Surg 14(Suppl 1):84S-89S]. SDF-1 is a potent chemotactic and angiogenic factor that stimulates recruitment of inflammatory cells. In the current study, we proposed that the resident cells in subacromial bursal tissue produce SDF-1, which can play a role in the inflammatory reponse of bursal tissue, and that this chemokine can be regulated by steroid (dexamethasone) and nonsteroidal anti-inflammatory medications (NSAIDs). Twenty-two subacromial bursa tissues (18 bursitis and 4 normal bursa) were obtained intraoperatively from patients during shoulder surgery and analyzed using the cDNA Array technique in accordance with an IRB approved protocol. cDNA array results were confirmed with real-time reverse transcription-polymerase chain reaction (RT-PCR). Bursal cells (from 4 normal bursa, 3 bursitis) and two normal bone marrow with whole tissue explants were cultured for one passage. Cell culture supernatants were collected and SDF-1 protein was detected with enzyme-linked immunosorbent assay (ELISA). Cultured bursal cells were treated with a COX-2 inhibitor and dexamethasone, and cells was harvested at 1-day and 4-day intervals. SDF-1 expression was evaluated by real-time RT-PCR and ELISA. cDNA Array analysis demonstrated that the gene expression of SDF-1 was increased in patients with subacromial bursitis compared to controls (p < 0.05). Real-time RT-PCR also revealed that the mRNA expression of SDF-1 in bursitis tissue is increased 10-fold over control tissue. While the normal bursal cells produced negligible amounts of SDF-1 protein, cultured cells derived from bursitis lesion released as much SDF-1 protein (235 pg/100,000 cells) as normal bone marrow stromal cells (283 pg/100,000 cells) as measured by ELISA. The addition of a COX-2 inhibitor and dexamethasone to bursitis cell lines led to decreased SDF-1 expression levels compared to untreated bursitis cell lines. These studies demonstrate that there is a significant elevation of SDF-1 expression in the subacromial bursa of patients with rotator cuff disease. Furthermore, this chemokine can be downregulated by COX-2 inhibitors and steroids. These results provide biologic evidence for the use of steroid and NSAIDs in the treatment of subacromial bursitis. In the future, targeted inhibition of molecules such as SDF-1 in the subacromial bursa may present a therapeutic strategy that may avoid the side effects of these other (steroid and NSAID) medications.

mu-Calpain regulates receptor activator of NF-kappaB ligand (RANKL)-supported osteoclastogenesis via NF-kappaB activation in RAW 264.7 cells.

To clarify the role of calpain in the receptor activator of NF-kappaB ligand (RANKL)-supported osteoclastogenesis, RANKL-induced calpain activation was examined by using murine RAW 264.7 cells and bone marrow-derived monocyte/macrophage progenitors. We found that calpain activity increased in response to RANKL in both cell types based on alpha-spectrinolysis and that mu-calpain, rather than m-calpain, was activated during RANKL-supported osteoclastogenesis in RAW 264.7 cells. Overexpression of mu-calpain clearly augmented RANKL-supported osteoclastogenesis in RAW 264.7 cells, thereby implicating its pivotal role in this process. Cell-permeable calpain inhibitors, including calpastatin and calpeptin, were sufficient to suppress RANKL-supported osteoclastogenesis based on decreased expression of the osteoclastogenic marker, matrix metalloproteinase 9, and the generation of tartrate-resistant acid phosphatase-positive multinucleated cells in both cell types. Calpain inhibitors suppressed NF-kappaB activation via inhibition of the cleavage of inhibitor of NF-kappaB(IkappaBalpha)in RAW 264.7 cells. Taken together, our findings suggest that mu-calpain is essential to the regulation of RANKL-supported osteoclastogenesis via NF-kappaB activation.

Pelvic motion during total hip arthroplasty with translateral and posterolateral approaches.

We devised a special instrument to assess intraoperative pelvic motion and used this device to measure intraoperative pelvic motion in three dimensions. A total of 100 total hip arthroplasties (THAs) were performed using this device. Two approaches were utilized: 52 THAs were performed with the posterolateral approach and the remaining 48 with the translateral approach. The average angle of pelvic tilt in the THAs with the translateral approach was less than that with the posterolateral approach. The average internal rotation angle was 1.75 degrees with the translateral approach and 14.25 degrees with the posterolateral approach. With the posterolateral approach, the internal rotation of the pelvis frequently occurred during retraction of the femur using a Hohmann's retractor placed at the anterior rim of the acetablum, with flexion and internal rotation of the affected hip.

Effect of calf-thigh intermittent pneumatic compression device after total hip arthroplasty: comparative analysis with plantar compression on the effectiveness of reducing thrombogenesis and leg swelling.

The purpose of this study was to evaluate the efficacy of two intermittent pneumatic compression devices as prophylaxis against intravascular coagulation and leg swelling following total hip arthroplasty. We studied 121 patients by assessing thrombogenesis using the D-dimer level before and after total hip arthroplasty. In addition, the patients' postoperative swelling was evaluated by measuring the thigh and lower leg circumference. Altogether, 58 patients were assigned to the calf-thigh pneumatic compression group, and the other 63 were assigned to the plantar compression group; the two pneumatic compression devices were compared to evaluate which was more effective for reducing thrombogenesis. At 7 days postoperatively, the mean D-dimer levels of the calf-thigh compression group and the plantar compression group were 8.86 and 9.26 microg/ml, respectively. There was no significant difference ( P = 0.697) between the two groups. However, the increased ratio of the circumference of the thigh, which was compared after arthroplasty, averaged 1.22% in the calf-thigh compression group and 3.19% in the plantar compression group, which was significantly different ( P << 0.01). Calf-thigh pneumatic compression was found to be more effective than plantar compression for reducing thigh swelling during the early postoperative stage.

The effect of posterolateral reconstruction on range of motion and muscle strength in total hip arthroplasty.

Posterolateral reconstruction of the posterior capsule, piriformis tendon, and external rotators in total hip arthroplasty improves the stability of the hip joint. This study was performed to evaluate the effect of this reconstruction on range of motion (ROM) and circumferential muscle strength. We selected 58 limbs of 29 patients. Posterolateral reconstruction was performed in 13 patients (reconstruction group). Posterolateral reconstruction was not performed in 16 patients (nonreconstruction group). No significant differences were seen in preoperative and postoperative ROM between the 2 groups. The reconstruction group had significantly higher abduction muscle strength (P<.0001) and external rotation muscle strength (P<.01) than the nonreconstruction group. Posterolateral reconstruction may be effective in promoting the recovery of abduction and external rotator muscle strength, and it can improve joint stability without limiting ROM.

Vascular anatomy for rotational acetabular osteotomy: cadaveric study.

Rotational acetabular osteotomies are performed to correct dysplastic hips in young adults. However, there is a potential risk of intrapelvic vascular injury. To define the relation of these vascular structures to the bone around the acetabulum, we measured the distance and direction from the anteroinferior iliac spine to the external iliac artery and from the base of the superior pubic ramus to the obturator artery in 34 cadaveric hemipelves (17 male, 17 female; 19 left, 15 right). The distance to the external iliac artery was significantly shorter in females (average 31.7 mm) than in males (average 38.2 mm); and the distance to the intrapelvic entry portal of the obturator canal, through which the obturator artery passes, was significantly shorter in females (average 27.2 mm) than in males (average 33.4 mm). In addition, the external iliac artery was located significantly more ventral and closer to the anteroinferior iliac spine in right hemipelves than in left hemipelves. The intrapelvic entry portal of the obturator canal was located more caudodorsal to the base of the superior pubic ramus in females than in males. Care should thus be taken during surgery in light of our findings.

Relationship between radiographic measurements of reconstructed hip joint position and the Trendelenburg sign.

We evaluated 60 limbs, including 34 primary total hip arthroplasties in 30 patients (mean age, 56 years) at a minimum of 2 years postoperatively. Femoral offset ratio (%FO) was calculated by dividing the femoral offset by the distance between the centers of the bilateral femoral heads on radiographs. The tilt angle of the pelvis by the Trendelenburg test was measured using the magnetic sensor system. In the limbs having a negative Trendelenburg sign after reconstruction, the %FO averaged 20.1% (range, 14.7% to 24.7%), and the tilt angle of the pelvis averaged +0.8 degrees (range, -1.0 degrees to +5.0 degrees ). The tilt angle of the pelvis correlated positively with %FO (P=.0160, r=0.407). The reconstructed hip joint position is crucial to improve hip abductor function.