These items originally appeared in AAOS Headline News Now, a thrice-weekly enewsletter that keeps AAOS members up to date on clinical, socioeconomic, and political issues, with links to more detailed information. Subscribe at www.aaos.org/news/news.asp (member login required)

Patient safety
Compartment syndrome—Findings published in the Journal of Orthopaedic Trauma (online) suggest that direct measurement of tissue oxygenation may help diagnose acute compartment syndrome. The researchers used a dog model of both compartment syndrome and tourniquet-based ischemia. With application of tourniquet ischemia, they found that partial pressure of oxygen (PmO2) fell from 38.40 mmHg to 1.30 mmHg, and rose after release of the tourniquet to 39.81 mmHg. Elevated compartment pressure induced by infusion was relieved by fasciotomy. In addition, PmO2 readings in the infusion model were significantly higher prior to compartment syndrome than during, and rebounded following fasciotomy. The researchers note that PmO2 can be directly measured in real time with a polarographic tissue oxygen probe, thus providing a way to diagnose compartment syndrome.

Blood guidelines—According to findings presented at the annual meeting of the American College of Surgeons National Surgical Quality Improvement Program, the adoption of blood utilization guidelines was associated with a 30 percent reduction in blood use at a single center. The research team revised the hospital's computerized provider order entry system to allow blood orders to be based on a specific assessment of each case rather than a standard order of two units. In addition, the team developed guidelines for perioperative handling, including:

• when more than one unit of blood is ordered, it is sent in a cooler rather than via pneumatic tube
• coolers were reconfigured to optimize temperature management
• a specific member of the staff is tasked with "ownership" of the blood products, including returning unused product to the blood bank
• individual unit wastage is reported to clinical leaders for review, with aggregate data reported monthly

Reducing readmissions—Data from a study published in JAMA Surgery (online) suggest that loss of independence (LOI) may be associated with postoperative readmission and death after discharge for older patients. The authors conducted a retrospective cohort study of 5,077 patients with a mean age of 75 years. They found that increasing age was associated with increased risk of LOI. After adjustment, the authors found that LOI was strongly associated with readmission and postoperative complication. In addition, LOI was the strongest factor associated with death after discharge, while postoperative complication was not significantly associated with death after discharge.
Chronic opioid use—According to data published in the journal JAMA Internal Medicine (online), total hip arthroplasty (THA) and total knee arthroplasty (TKA) may be associated with an increased risk of chronic opioid use postoperatively. The research team conducted a retrospective analysis of 641,941 opioid-naïve surgical patients who underwent one of 11 surgical procedures, including THA or TKA, and 18,011,137 opioid-naïve nonsurgical patients. Among surgical patients, the incidence of chronic opioid use in the first postoperative year ranged from 0.119 percent for Cesarean delivery to 1.41 percent for TKA. The research team found that, with five exceptions, all of the surgical procedures reviewed were associated with an increased risk of chronic opioid use, with odds ratios ranging from 1.28 for Cesarean delivery to 5.10 for TKA. Overall, male sex, age older than 50 years, and preoperative history of drug abuse, alcohol abuse, depression, benzodiazepine use, or antidepressant use were associated with increased likelihood of chronic opioid use among surgical patients.

Pediatric compartment syndrome—A study published in The American Journal of Sports Medicine (AJSM; online) examines outcomes and demographics of chronic exertional compartment syndrome (CECS) among pediatric patients. The research team conducted a retrospective review of 155 patients (136 females) 18 years or younger who were treated surgically for CECS with compartment release at a single institution. The research team states that all patients had leg pain and that 8 patients (5 percent) also had neurologic symptoms; 131 patients (85 percent) had bilateral symptoms requiring bilateral compartment release. The most common primary sports were running (25 percent), soccer (23 percent), and field hockey (12 percent), with 50 percent of patients being multisport athletes. Of 286 legs, 138 (48 percent) had only anterior and/or lateral compartments released, while 84 (29.4 percent) had all four compartments released. Overall, 79.5 percent of patients returned to sport. Of 250 legs for which outcomes analysis was performed, 47 (18.8 percent) had recurrent CECS requiring reoperation at a median of 1.3 years after initial compartment release. Legs with only anterior and/or lateral compartment released had 3.4 times the likelihood of reoperation compared with legs that had all four compartments released.

Hip and knee
Meniscal tear—According to a study conducted in Denmark and published in The BMJ (online), supervised exercise therapy may be an acceptable treatment option for certain patients with degenerative meniscal tears. The researchers conducted a randomized, controlled trial of 140 adults (mean age: 49.5 years) with degenerative medial meniscal tears verified by magnetic resonance imaging. Patients were treated with either 12 weeks of supervised exercise therapy alone or arthroscopic partial meniscectomy alone. At 2-year follow-up, no clinically relevant difference across cohorts was found regarding change in Knee injury and Osteoarthritis Outcome score (KOOS4), defined as the mean score for four of five KOOS subscale scores (pain, other symptoms, function in sport and recreation, and knee-related quality of life). In addition, at 3-month follow-up, patients in the exercise group displayed greater increases in thigh muscle strength compared to those in the surgical group.

Rehabilitation and ACLR—Findings published in AJSM (online) suggest that preoperative rehabilitation may improve postoperative outcomes for up to 2 years following anterior cruciate ligament reconstruction (ACLR). The research team compared outcomes from two cohorts, the Delaware-Oslo ACL Cohort (DOC), in which patients were treated with extended preoperative rehabilitation, including neuromuscular training, and the Multicenter Orthopaedic Outcomes Network (MOON) cohort, in which patients did not undergo extended preoperative rehabilitation. After adjustment for baseline International Knee Documentation Committee (IKDC) score and KOOS, the research team found that DOC patients displayed significant and clinically meaningful differences in IKDC and KOOS scores at 2-year follow-up. In addition, they noted 72 percent of DOC patients returned to preinjury sports, compared to 63 percent of MOON patients.

Autograft and ACLR—Data from a study published in Clinical Orthopaedics and Related Research (CORR; online) suggest that both single-bundle (SB) and double-bundle (DB) ACLR with 6- to 8-stranded hamstring autograft may offer satisfactory outcomes in the mid-term. The authors conducted a randomized, controlled trial of 80 patients with chronic ACL rupture who underwent either SB or DB ACL reconstruction with a 6- to 8-stranded hamstring autograft. Of 68 patients available at mean 80-month follow-up, no significant differences were found across cohorts in functional scores, incidence of pivot shift, range of motion, Lachman test, KT-2000 arthrometer anterior laxity, or time and level of return to sport. The authors note that there were two traumatic instability failures and two 5 degrees extension restrictions in the DB group, and no failures or 5 degrees extension restrictions observed in the SB group.

Spine
BMP—Findings from a study published in The Journal of Bone & Joint Surgery (July 6) suggest that use of recombinant bone morphogenetic protein (BMP) may not be associated with increased risk of cancer or mortality for older adults who undergo lumbar arthrodesis. The authors conducted a case-cohort study of 7,278 patients aged 65 years or older who had undergone a lumbar arthrodesis between 2004 and 2011. They found that treatment with BMP was not associated with overall cancer risk in univariate analyses or after adjustment for demographic characteristics, comorbidities, hospital size, history of cancer, and calendar year. In addition, the authors note that individual cancer types were also not significantly elevated in BMP users compared with nonusers, nor was BMP use associated with a new cancer in patients who had cancer prior to undergoing lumbar arthrodesis or with mortality after a cancer diagnosis.

Degenerative lumbar spine disease—A study published in CORR (August) examines a potential relationship between degenerative disc disease (DDD) and lumbar-pelvic-femoral alignment prior to surgery among patients who undergo THA. The research team reviewed data on 242 patients undergoing primary THA who had preoperative low-dose EOS® spine-to-ankle lateral radiographs in standing and sitting positions. Patients were excluded for scoliosis, spondylolysis, not having five lumbar vertebrae, surgical or disease fusion, or poor image quality attributable to high body mass index (BMI). After adjustment for age, sex, and BMI, the researchers found that patients with DDD spines had a mean of 5 degrees more posterior pelvic tilt and 7 degrees less lumbar lordosis in the standing position compared with patients without radiographic arthrosis. In the sitting position, patients with DDD spines had 4 degrees less posterior pelvic tilt. Finally, from standing to sitting position, patients with DDD spines experienced 10 degrees less spine flexion and 10 degrees more femoroacetabular flexion. The researchers write that, when planning THA, "it may be important to consider which patients sit with less posterior pelvic tilt and those who rotate their pelvises forward to achieve a sitting position, as both mechanisms will limit or reduce the functional anteversion of the acetabular component in a patient with a THA."

Trauma
Tibial shaft fracture—Data from a study published in the Journal of Orthopaedic Trauma (July) suggest that immediate weight-bearing after intramedullary (IM) nailing of unstable tibial shaft fractures may not be linked to an increased risk of adverse events or complications. The authors conducted a randomized, controlled trial of 68 adult patients (70 tibial shaft fractures) who were allowed immediate weight-bearing-as-tolerated or required to be non–weight-bearing for the first 6 postoperative weeks. At mean 22.1-week follow-up, no statistical difference across cohorts were found in observed time to union, complication rates, or Short Musculoskeletal Function Assessment score. In addition, the authors note that there was no fracture loss of reduction leading to malunion in either cohort.

Foot and ankle
Hallux valgus—A study published in Foot & Ankle International (July) finds similar long-term outcomes for patients undergoing hallux valgus correction using chevron or scarf osteotomy. The researchers conducted a randomized, controlled trial of 37 feet treated with chevron osteotomy and 36 feet treated with scarf osteotomy. At 14-year follow-up, they found that recurrence of hallux valgus in 28 feet in the chevron group and 27 feet in the scarf group had developed recurrence of hallux valgus. In addition, no patients in the chevron group and one patient in the scarf group had a reoperation of the same toe. Finally, current visual analog scale pain scores and results from the Short Form 36 questionnaire, the Manchester-Oxford Foot Questionnaire, and American Orthopaedic Foot & Ankle Society (AOFAS) rating system for the hallux metatarsophalangeal-interphalangeal scale did not significantly differ between groups.

Shoulder and elbow
Shoulder dislocation—Findings presented in Paper 103 at the annual meeting of the American Orthopaedic Society for Sports Medicine (AOSSM) suggest that early surgical intervention may be appropriate for many young, athletic patients with shoulder dislocation. The authors reviewed data on 121 patients (mean age 19 years) who underwent arthroscopic Bankart repair across eight fellowship-trained surgical practices. Overall, 53 patients were determined to have recurrent dislocations and 68 had a first-time dislocation. At mean 51-month follow-up, the authors found that the postoperative instability rate in the first-time dislocation group was 9 percent, compared to 47 percent in the recurrent dislocation group. In addition, the first-time dislocation group reported a 7 percent rate of repeat operation to address instability, compared to a 32 percent rate in the recurrent dislocation group. Finally, the Simple Shoulder Test score in the first-time dislocation group was 11.4 and 11 in the recurrent dislocation group. The authors argue that "young, athletic patients with shoulder instability should be offered early surgical intervention to lower the risk of postoperative instability and reoperation."

Biologics
Muscle regeneration—Researchers have demonstrated that the ß1-integrin protein is critical for maintaining the cycle of hibernation, activation, proliferation, and return to hibernation in muscle stem cells. The findings, published in Nature Medicine (online), could have promising implications for therapeutic interventions to regenerate muscle in older patients, particularly after injury or surgery. The researchers found that the function of ß1-integrin is diminished in aged muscle stem cells. Yet, when the protein was artificially activated in mice with aged muscles, their regenerative abilities were restored to youthful levels. Regeneration, strength, and function also improved when the treatment was applied in animals with muscular dystrophy, demonstrating the protein's potential importance for the treatment of muscle disorders.