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AAOS Now

Published 4/1/2017

Second Look — Clinical

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
Heparin thromboprophylaxis—
Findings from a study conducted in Norway and published in The New England Journal of Medicine (Feb. 9) shed doubt on the efficacy of administration of low-molecular-weight heparin for thromboprophylaxis following knee arthroscopy or lower leg casting. The authors conducted two parallel, pragmatic, multicenter, randomized, controlled, open-label trials with blinded outcome evaluation. In the first trial, 1,541 knee arthroscopy patients were randomized to receive 8 days of either low-molecular-weight heparin or placebo following arthroscopy. Venous thromboembolism (VTE) occurred in 5 of 731 patients (0.7 percent) in the treatment group and in 3 of 720 patients (0.4 percent) in the control group. In the second trial, 1,435 patients treated with casting of the lower leg were randomized to receive low-molecular-weight heparin or placebo during the full period of immobilization. VTE occurred in 10 of 719 patients (1.4 percent) in the treatment group and in 13 of 716 patients (1.8 percent) in the control group.

Chlorhexidine gluconate—The U.S. Food and Drug Administration (FDA) states that rare but serious allergic reactions have been reported with skin antiseptic products containing chlorhexidine gluconate. Chlorhexidine gluconate is mainly available in over-the-counter (OTC) products to clean and prepare the skin prior to surgery and injections in order to help reduce the likelihood of skin infection. Such products are available under many different brand names and as generics. The agency notes that the number of reports of serious allergic reactions to chlorhexidine gluconate products has increased over the last several years and is therefore requesting manufacturers of OTC products to add a warning about this risk to drug labels. Prescription chlorhexidine gluconate products already contain such a warning.

Periprosthetic joint infection—Findings published in Clinical Orthopaedics and Related Research (CORR; February) suggest that the alpha-defensin assay may be a reliable diagnostic tool for the identification of periprosthetic joint infection (PJI). The authors conducted a prospective study of 156 patients who underwent total joint arthroplasty (65 knees, 91 hips), 29 of whom received a confirmed diagnosis of PJI. They found that the alpha-defensin immunoassay produced a sensitivity of 97 percent, specificity of 97 percent, positive predictive value of 88 percent, and negative predictive value of 99 percent. Among four false-positive patients, the authors note that two had metallosis and one had polyethylene wear, and the false-negative patient presented with a draining sinus. They argue that follow-up evaluation should be conducted to estimate longer-term performance of the test.

Sarcopenia—According to a study published in The Journal of Bone & Joint Surgery (JBJS; Feb. 1), sarcopenia may often be associated with acetabular fractures in older patients, and is linked to increased complication and mortality rates. The research team reviewed data on 99 patients with acetabular fracture and recorded body mass index (BMI) and adequate computed tomography scans from the Rhode Island Hospital Trauma Database. Of those, 42 patients had sarcopenia and 57 did not. They found that sarcopenia was more common in male patients and in patients with lower BMI. Overall, fractures in patients without sarcopenia were generally associated with a higher-energy mechanism of injury than among patients with sarcopenia. Compared to no sarcopenia, the research team found that sarcopenia was significantly associated with increased 1-year mortality and likelihood of anterior column fracture.

Smoking—Findings published in JBJS (Feb. 15) suggest that smokers may be at increased risk of reoperation for infection following total joint arthroplasty (TJA). The authors reviewed data on 15,264 TJA patients (17,394 procedures), of whom 1,371 (9.0 percent) were current smokers, 5,195 (34.0 percent) were former smokers, and 8,698 (57.0 percent) were nonsmokers. Overall, former smokers reported a median of 22.2 years (range, 0.2 to 60 years) of abstaining from smoking prior to the surgical procedure. The authors found that current smokers were significantly more likely than nonsmokers to undergo reoperation for infection, while former smokers were at no increased risk. However, the number of cigarette packs smoked per decade was independently associated with an increased risk of 90-day nonsurgical readmission regardless of smoking status.

Hip
Pseudotumors—
A study published in CORR (February) examines the natural history of asymptomatic pseudotumors in metal-on-metal (MOM) total hip arthroplasty (THA). The research team reviewed information on 71 patients who underwent MOM THA, 23 of whom (32 percent) had a positive ultrasound scan for pseudotumor at early follow-up. Of those, eight patients underwent revision THA (35 percent of those with a positive scan). Of the remaining 15 patients, 12 had persistent pseudotumor, two resolved, and one was lost to follow-up. Six patients (13 percent) who had a normal early ultrasound scan showed new ultrasound findings at delayed follow-up, and of those, four were conclusively diagnosed as pseudotumor, and one underwent revision. Of five patients in whom the volume of pseudotumor decreased on ultrasound at midterm follow-up, three showed a decrease in serum trace ions levels and two showed an increase. In two of six cases, new-onset pseudotumors at midterm follow-up were linked to an increase in serum trace metal ions at midterm follow-up.

Prosthetic joint infection—Findings from a study conducted in Denmark and published in CORR (online) suggest that revision for PJI within 1 year following primary THA may be linked to an increased risk of mortality during the first year after the revision surgery. The research team conducted a population-based cohort study of 68,504 primary THAs among 59,954 patients, of which 445 primary THAs underwent revision for PJI and 1,350 underwent revision for other causes. They found that, within 1 year of primary THA, 8 percent of patients who underwent revision for PJI died. Adjusted relative mortality risk for patients with revision for PJI was 2.18 compared with patients who did not undergo revision, and 1.87 compared with patients with aseptic revision. The research team also notes that patients with enterococci-infected THA had a 3.10 higher mortality risk compared to patients infected with other bacteria.

Gait analysis—According to a study in the Journal of Orthopaedic Research (February), gait analysis may augment clinical scores in predicting a patient's clinical response to THA. The researchers analyzed data on 124 patients (mean age 61 years) who were evaluated both before and 1 year after THA using quantitative gait analysis and Harris Hip Scores (HHS). They found that 11.3 percent of participants were nonresponders, based on Outcome Measures in Rheumatology/Osteoarthritis Research Society International responder criteria. Prior to surgery, the researchers found that range of motion was 26 percent higher for nonresponders than responders, but the peak external rotation moment was 30 percent lower. Preoperative gait and HHS predicted response with a sensitivity of 71.4 percent and a specificity of 99.1 percent.

Rehabilitation—Findings presented at the annual meeting of the Association of Academic Physiatrists suggest that typical postoperative precautions followed after hip arthroplasty may increase inpatient rehabilitation time and slow overall recovery. The research team conducted a retrospective review of 68 hip arthroplasty patients, 31 of whom were admitted to inpatient rehabilitation without postoperative surgical precautions and 37 of whom were admitted with precautions. At discharge, they found that both groups had made similar progress in overall functional independence measures (FIM) scores and daily FIM improvements. However, the average length of stay for patients who entered rehabilitation without postoperative precautions typically was 9 days, compared to 12 days for patients with postoperative precautions.

Knee
Hamstring tendon graft—
A study published in The American Journal of Sports Medicine (online) suggests that hamstring tendon graft combined with anterolateral ligament reconstruction (HT+ALL) may offer reduced failure rates compared to bone–patellar tendon–bone (B-PT-B) graft or quadrupled hamstring tendon (4HT) graft for patients who undergo anterior cruciate ligament (ACL) reconstruction. The research team conducted a prospective, cohort study of 502 patients (mean age 22.4 years). At mean 38.4-month follow-up, they found that graft rupture rates were 4.13 percent for HT+ALL grafts, 10.77 percent for 4HT grafts, and 16.77 percent for B-PT-B grafts. Other prognosticators of graft failure included age ≤25 years and a preoperative side-to-side laxity >7 mm. The research team noted that HT+ALL graft was also associated with increased likelihood of returning to preinjury levels of sport compared to 4HT graft, but not B-PT-B graft.

Reoperation risk—According to a study in JBJS (Feb. 1), prior ACL reconstruction may be linked to increased surgical time and risk of early reoperation following total knee arthroplasty (TKA). The research team conducted a matched cohort study of 244 patients who underwent TKA, of whom 122 had a history of ACL reconstruction and 122 did not. At mean follow-up of 3.3 years in the ACL cohort and 3.0 years in the control cohort, they found no significant difference between groups in Knee Society Score or flexion. However, 50 percent of patients (61 of 122) in the ACL group required implant removal at the time of TKA, and mean surgical time was 88 minutes in the ACL group and 73 minutes in the control group. There were 11 reoperations in the ACL group—including 4 for periprosthetic infection—and 2 reoperations in the control group.

Shoulder and elbow
Latarjet procedure—
Findings published in Arthroscopy (February) suggest that use of the arthroscopic Latarjet procedure may be associated with less postoperative pain compared to the mini-open procedure for patients treated for anterior shoulder instability. The authors conducted a prospective, comparative study of 58 patients, 22 of whom were treated using a mini-open approach and 36 of whom were treated arthroscopically. At mean 29.8-month follow-up, they found significantly less pain in the arthroscopy group compared to the mini-open group during postoperative week 1, with comparable consumption of analgesics. In addition, the arthroscopic Latarjet procedure resulted in a more lateral coracoid bone block and an improved equatorial position compared to the mini-open technique. Overall, three patients in the arthroscopy cohort and zero in the mini-open cohort underwent revision surgery.

Spine
Spinal deformity—
A study published in the Journal of the AAOS (February) suggests that spinal deformity correction may cause significant acetabular component repositioning for patients who have undergone THA. The researchers reviewed data on 27 patients with unilateral THA who underwent thoracolumbar fusions for adult spinal deformity from the pelvis to L1 or above. They found that postoperative acetabular tilt (AT) decreased significantly from baseline, with greater AT changes among patients with three-column osteotomy. Overall, AT was significantly correlated with changes of pelvic tilt and lumbar lordosis (LL), with AT decreased (ie, retroverted) 1° for every 1.13° of pelvic tilt or 3.23° of LL correction. The coronal plane acetabular cup abduction angle did not change substantially.

Lumbar microdiskectomy—A research letter published in JAMA Surgery (online) compares patient-reported outcomes for older and younger patients following lumbar microdiskectomy. Researchers in Norway reviewed registry data on 5,575 patients who underwent lumbar microdiskectomy, 380 of whom were aged 65 years or older at the time of surgery. They found that all patients displayed significant improvement, and there were no age-related differences in terms of improved quality of life or leg pain after surgery. However, the researchers note that patients aged 65 years and older were more likely to experience minor complications, both in the hospital and within 3 months of discharge.

Hand and wrist
Distal radius fracture—
According to a study in The Journal of Hand Surgery (online), both volar locking plates and fragment-specific fixation may offer similar outcomes for treatment of primarily nonreducible or secondarily redisplaced distal radius fractures, although fragment-specific fixation may be linked to an increased risk of complication. The authors conducted a randomized, controlled trial of 50 adult patients who underwent open reduction and internal fixation (ORIF) using volar locking plates (n = 25) or fragment-specific fixation (n = 25). At 12-month follow-up, they found no significant difference across cohorts in grip strength, range of motion, or median Quick Disabilities of the Arm, Shoulder, and Hand score. However, the overall complication rate was 21 percent in the volar locking plate group and 52 percent in the fragment-specific group.

Foot and ankle
Ankle fracture—
A study in the Journal Foot & Ankle International (online) examines factors that may be predictive of decreased physical function for patients who undergo surgery for ankle fracture. The authors retrospectively reviewed data on 142 adult patients (mean age 52.7 years) who underwent surgical management of closed ankle fracture with a minimum 2-year follow-up. At mean 6.3-year follow-up, they found that independent predictors of decreased physical function included higher age, higher American Society of Anesthesiologists (ASA) class, and higher BMI, while predictors of increased pain interference included higher ASA class and lower BMI. The authors write that overall, ASA class had the strongest effect on both physical function and pain.