Comparing 2 implant systems for restoring hip geometry
Femoral components with a modular junction at the base of the neck (two modular junction components) have increased the options for restoring femoral offset and leg length during total hip arthroplasty (THA). Investigators evaluated whether a femoral component with 2 modular junctions would predict by templating more frequent restoration of preoperative offset and leg length abnormalities than a component with a single modular junction.
Investigators reviewed the preoperative templating data for 100 primary THAs that were performed using single modular junction implants with a neutral version stem and 100 THAs with 2 modular junction implants. They compared the frequency with which the desired leg length and offset were restored completely in both groups.
Offset and leg lengths were restored to within 1 mm in 85% of cases with 2 modular junction implants and in 60% of cases with single modular junction implants. An anteverted or a retroverted neck was used in 25% of the procedures that were performed with 2 modular junction stems.
Femoral components with 2 modular junctions resulted in more frequent ability to restore femoral offset and leg length than those with a single modular junction. Investigators caution that the advantage of clinical flexibility conferred by 2 modular junctions is somewhat offset by the potential for prosthetic mechanical failure and increased third-body wear, corrosive debris, and prosthetic cost.
Source: Archibeck MJ, Cummins T, Carothers J, Junick DW, White RE Jr.
A comparison of two implant systems in restoration of hip geometry in arthroplasty. Clin Orthop Relat Res. 2010 Nov 17. [Epub ahead of print]
Quadriceps strength: How important after ACL?
Quadriceps strength and activation may improve recovery after anterior cruciate ligament (ACL) revision. In a recent study, researchers documented deficits in bilateral quadriceps central activation and osteoarthritis in patients who underwent revision ACL reconstruction.
The study involved 21 patients assessed 14 to 85 months after revision ACL reconstruction. Bilateral quadriceps strength testing consisted of maximal voluntary isometric contractions (MVICs) with the knee bent 90 degrees. Researchers calculated quadriceps central activation ratio (CAR) using the superimposed burst technique. A fellowship-trained orthopaedic surgeon used the International Knee Documentation Committee (IKDC) grading system to rate the severity of degeneration on bilateral standing anteroposterior radiographic views with the knees flexed and lateral views with the knees fully extended.
Average CARs were lower in reconstructed limbs than in contralateral limbs (83.9 ± 12.0% vs. 85.5 ± 9.5%, respectively). Average normalized MVIC torque also was lower in reconstructed limbs than in contralateral limbs (2.5 ± 1.0 Nm/kg vs. 2.7 ± 1.0 Nm/kg, respectively).
Patient age at the follow-up assessment was related to the severity of knee joint degeneration, especially the medial, anterior, and patellofemoral compartments. More severe degeneration in the patellofemoral joint was correlated with lower CARs in younger patients and lower normalized MVIC torque values in older patients.
Source: Hart JM, Turman KA, Diduch DR, Hart JA, Miller MD. Quadriceps muscle activation and radiographic osteoarthritis following ACL revision. Knee Surg Sports Traumatol Arthrosc. 2010 Nov 26. [Epub ahead of print]
Ankle sprains by the numbers
Much is known about ankle sprains among athletes, but until now, researchers have paid scant attention to sprains in the general population.
Investigators used the National Electronic Injury Surveillance System (NEISS) to analyze demographic data relating to all patients presenting to emergency departments with ankle sprain injuries between 2002 and 2006. During the study period, an estimated 3,140,132 ankle sprains occurred--a rate of 2.15 sprains per 1000 person-years in the United States.
The data indicate that ankle sprains are most common among people 10 to 19 years of age. The peak incidence of ankle sprains is among teenagers of both sexes, ages 15 to 19 (7.2 per 1000 person-years). Males between 15 and 24 years of age have substantially higher rates of ankle sprain than females in the same age range, but women older than 30 have higher rates than their male counterparts.
Half of all ankle sprains occur during athletic activity. Sports that account for the highest percentage of ankle sprains are basketball (41.1%), football (9.3%), and soccer (7.9%).
Source: Waterman BR, Owens BD, Davey S, Zacchilli MA, Belmont PJ Jr. The epidemiology of ankle sprains in the United States. J Bone Joint Surg Am. 2010;92(13):2279-2284.
Gauging long-term results after shoulder resurfacing
Shoulder resurfacing has regained popularity in recent years, but what are its long-term results in terms of patient satisfaction and implant survival?
Recent study results indicate that shoulder resurfacing is successful for most patients. The procedure is associated with high rates of patient satisfaction, long-term survival of the humeral prosthesis, and few complications.
The study involved 61 patients who underwent shoulder resurfacing procedures (74 shoulders). Patients were followed for a minimum of 20 years or until death. Average patient age at surgery was 58 years.
There were 41 total resurfacing procedures and 33 hemi-resurfacing procedures. The humeral component involved a cup with a short central peg that was affixed with or without cement. The glenoid was resurfaced with a cemented polyethylene or polyurethane component.
Patient satisfaction was 95%, and survival of the humeral prostheses was 96%. There were no periprosthetic fractures, dislocations, or infections. Two humeral components were revised to stemmed prostheses (1 for loosening and 1 for unexplained pain). One was revised from a cementless to a cemented resurfacing prosthesis. Twelve cemented polyethylene glenoid prostheses had radiolucencies, but only 3 produced symptoms requiring revision surgery. Three polyurethane glenoid prostheses showed severe wear radiographically, but none was loose or required revision surgery. There were 7 revision procedures, 6 of which produced good results.
Source: Pritchett JW. Long-term results and patient satisfaction after shoulder resurfacing. J Shoulder Elbow Surg. 2010 Nov 22. [Epub ahead of print]
Decreasing bone-graft infection
Do vancomycin-modified bone allografts resist bacterial colonization and biofilm formation? To find out, investigators coupled the antibiotic to allografts and challenged them with S. aureus.
Investigators noted a uniform distribution of antibiotic on the allograft. After challenges with S. aureus for 6 hours, the covalently bonded vancomycin decreased colonization as a function of inoculum. The vancomycin-coated surface resisted biofilm formation, even in niches that are conducive to bacterial adhesion.
The antibiotic attachment to the allograft surface was robust, and the vancomycin was stable whether incubated in aqueous media or in air. Vancomycin levels remained at 75-100% of initial levels for 60 days.
Although the vancomycin-allograft combination inhibited gram-positive S. aureus colonization, which is in keeping with vancomycin's spectrum of activity, the vancomycin-modified allograft was readily colonized by gram-negative E. coli.
Initial toxicity measurements indicate that the vancomycin-modified allograft had no influence on osteoblast colonization or viability. Researchers conclude that vancomycin-modified allografts have great potential for decreasing bone graft-associated infections because the covalently tethered antibiotic is stable, active, retains its specificity, and doesn't exhibit toxicity.
Source: Ketonis C, Barr S, Adams CS, Shapiro IM, Parvizi J, et al. Vancomycin bonded to bone grafts prevents bacterial colonization. Antimicrob Agents Chemother. 2010 Nov 22. [Epub ahead of print]
Taking the measure of new imaging technology
Is it safe to exclude peripheral skeletal injuries on the basis of screening with the new Lodox Statscan (LS)? Also, can LS imaging provide adequate information for preoperative planning?
The LS is a digital low-radiation imaging device that provides full-body anterior and lateral views using enhanced linear slot-scanning technology.
Investigators conducted a study involving 245 consecutive patients age 16 years or older who sustained polytrauma and underwent LS imaging. The LS scans were reviewed and compared with plain radiographs or computed tomography scans, when they were available.
The sensitivity and specificity of LS were 73% and 100%, respectively, for peripheral skeletal injuries. Additional plain radiographs were obtained in 50% of cases, for reasons that included more precise resolution of the affected body part, an additional second or third plane, additional information regarding the fracture type and planning of the surgical approach, and preoperative planning of implant size and positioning on calibrated digitized films.
Investigators concluded that the high sensitivity and specificity of LS make it an efficient tool for patient screening in the emergency room. For diagnostic or preoperative uses, however, additional radiographic imaging often is required.
Source: Evangelopoulos DS, Deyle S, Brehmer T, Benneker LM, Hasler R, et al. The efficiency of full body radiography 'Lodox Statscan' in the detection of peripheral skeletal fractures in adult trauma patients. Injury Extra. 2010;41(12):132.
Improving shoulder function in patients with RA
Reverse shoulder arthroplasty could potentially restore biomechanical balance to patients with rheumatoid arthritis (RA) who develop superior migration of the humeral head after massive rotator cuff tears, but does the high incidence of reported glenoid failure apply to patients with RA?
Investigators analyzed pain relief and shoulder function after reverse arthroplasty in patients with RA. They compared results between primary and revision procedures, determined the incidence of scapular notching, and determined the complication rate.
Twenty-three patients (27 shoulders) who had reverse arthroplasty, including 18 primary and 9 revision arthroplasties, were assessed after a minimum follow-up period of 18 months. All patients were assessed preoperatively and postoperatively. Level of pain, range of motion, and Constant-Murley score were recorded, and new radiographs were obtained.
Reverse arthroplasty in patients with RA decreased pain and improved shoulder function with few complications. Visual analog scale scores for pain decreased from 8 to 1. Constant-Murley scores increased from 13 to 52; patients who underwent primary procedures had higher scores than those who had revisions. Three patients required revision surgery. Notching occurred in 52% of shoulders, but no loosening was observed.
Investigators suggest that this procedure should be considered for elderly patients with RA who have pain and poor active range of motion resulting from massive rotator cuff tears.
Source: Ekelund A, Nyberg R. Can reverse shoulder arthroplasty be used with few complications in rheumatoid arthritis? Clin Orthop Relat Res. 2010 Nov 12. [Epub ahead of print]
Artificial total disc replacement vs. fusion for the cervical spine
Cervical total disc replacement (CTDR) is no better than fusion in alleviating symptoms related to disc degeneration in the cervical spine, according to results from a systematic literature review. CTDR, however, is used increasingly as an alternative to fusion in patients who have pain or neurological symptoms in the cervical spine that don't respond to nonsurgical treatment.
According to the literature review, pain, disability, and quality of life improve about equally after each procedure. Both procedures have similar success alleviating symptoms related to disc degeneration in the cervical spine. Both procedures have similar complication rates. No evidence is available to compare CTDR and nonsurgical treatment.
Long-term improvement of health outcomes seems to be similar after CTDR and fusion; however, the quality of the studies reviewed was often severely limited. After either intervention, many patients still face problems.
Investigators don't recommend CTDR for routine use, but they note that many trials are ongoing and recommend future re-evaluation. They also note the need for research that compares the effectiveness of CTDR and conservative treatment.
Source: Zechmeister I, Winkler R, Mad P. Artificial total disc replacement versus fusion for the cervical spine: a systematic review. Eur Spine J. 2010 Oct 10. [Epub ahead of print]
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