Poor Prognosis of Patients Treated for Periprosthetic Joint Infection.

The study by Gomez et al., "The Fate of Spacers in the Treatment of Periprosthetic Joint Infection," evaluates the clinical course and success rate of treatment of periprosthetic joint infection with two-stage revision with spacer placement in the interim period. The current review critically analyzes the findings of this study and examines how these findings may influence patient care in the field of hip and knee replacement. Gomez et al. report sobering results of two-stage revision with spacer placement for periprosthetic joint infection. Nearly 20% of patients in their study who had a spacer placed never went on to get a new prosthesis and nearly 20% of those who did get a new prosthesis ultimately failed treatment. The authors reported a 7.5% mortality rate in the interstage period after resection arthroplasty. This study provides valuable information for counseling patients about the outcomes of treatment using spacers for infection after total joint arthroplasty. The results of this study also highlight the need for future investigation into better treatments for periprosthetic joint infections.

The Effect of Capitate Position on Coronal Plane Wrist Motion After Simulated 4-Corner Arthrodesis.

PURPOSE: The objective of this study was to examine the effect of altering the capitolunate relationship on coronal-plane wrist motion after scaphoidectomy and simulated 4-corner arthrodesis. Two positions of different capitolunate alignments were compared: "anatomic" (unchanged from pre-fusion) and "lunate-covered" (capitate translated to cover the lunate). We hypothesized that wrist resting posture would be altered and radial-ulnar motion would diminish after 4-corner arthrodesis in the lunate-covered position when compared with normal wrists. METHODS: Six human cadaveric limbs were disarticulated at the elbow and mounted on a custom jig. The resting position of the wrist was recorded with no load applied, followed by a load of 44 N applied to the flexor carpi radialis, extensor carpi radialis longus, and extensor carpi radialis brevis tendons to simulate radial deviation and to the flexor carpi ulnaris and extensor carpi ulnaris tendons to simulate ulnar deviation. Scaphoidectomy was performed and 2 methods of 4-corner arthrodesis with different capitolunate coronal alignments were studied in random order. Range of motion was compared using one-way analysis of variance and Bonferroni correction. RESULTS: The "lunate covered" wrist demonstrated significantly greater radial resting posture than that of the preoperative wrist. Under a 44 N load, the lunate-covered position had significantly greater radial motion than the preoperative radial motion. Wrists fused in the "anatomic" position did not differ significantly from the preoperative wrists in posture or range of motion. CONCLUSIONS: In this cadaveric model, complete covering of the capitate head by the lunate placed the wrist in increased radial deviation compared with the anatomic posture. Changes induced in the resting tension of the extrinsic wrist ligaments serve as a reasonable explanation for the increased radial posture and motion. In a clinical setting, these changes may affect postoperative wrist posture and function. CLINICAL RELEVANCE: Maintaining anatomic lunate position leads to preservation of greater wrist motion and anatomic alignment in a patient undergoing 4-corner arthrodesis.

In vitro elution characteristics of antibiotic laden BoneSource™, hydroxyapatite bone cement.

A calcium phosphate - hydroxyapatite (HA) bone cement was loaded with varying concentrations of tobramycin and vancomycin and the elution properties of these antibiotics were evaluated. Nine groups of antibiotic loaded cement cylinders (N = 6 in each group) were prepared and placed in saline for 28 days. Elution rates of tobramycin and vancomycin from the HA cement were evaluated at high, medium, and low doses of incorporated antibiotic. Tobramycin elution rates did not vary according to dose (0.36, 0.18, and 0.09g). Vancomycin elution rates were also not significantly affected by dose (0.1 , 0.05 , and 0.025 g). The combination of tobramycin and vancomycin increased the elution rate of vancomycin for the medium and low dose of tobramycin. The dose of tobramycin did not affect its elution rate from the cement in the combined groups. Importantly, the concentration of antibiotic eluent stayed above the minimum inhibitory concentration for the entire 28 days for all groups except the medium and low dose of vancomycin alone. Overall, elution rates of both tobramycin and vancomycin in the calcium phosphate-HA cement were comparable to those from polymethylmethacryltate beads in vitro.

The epidemiology of reoperation after flexor tendon repair.

PURPOSE: To describe the incidence of reoperation and the demographic factors that may be associated with reoperation after flexor tendon repair. METHODS: Using a New York statewide hospital administrative database covering an 8-year period, we examined unique patient discharges with an index procedure of flexor tendon repair for reoperation (re-repair or tenolysis). We compared the age, sex, race, and insurance type by reoperation status using standard univariate statistics and multivariate regression analysis. We performed trend analysis using the Cochran-Armitage trend test. RESULTS: From 1998 to 2005, there were 5,229 flexor tendon repairs with a frequency of reoperation of 6%; of these, 91% were in the first year after the primary procedure. Those who underwent reoperation were significantly older than those who did not undergo reoperation. Patients with workers' compensation were 63% more likely to undergo reoperation than those with other forms of insurance. Patients who had concomitant nerve repair during the index procedure were 26% less likely to undergo reoperation. The rate of reoperation did not change during the study period. CONCLUSIONS: These results may be useful in shaping research agendas to evaluate sociodemographic factors contributing to reoperations. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic II.

Complications after flexor tendon repair: a systematic review and meta-analysis.

PURPOSE: Although outcomes after flexor tendon repair have reportedly improved with modern treatment, complications are common. The purpose of this study was to determine the incidence of these complications and the potential contributory factors within the published literature. METHODS: We performed a systematic review of the available literature to identify publications in which patients with flexor tendon ruptures were surgically treated. We extracted demographics, zone of injury, core suture technique (only modified Kessler or a combination of techniques), use of epitendinous suture, and date of publication (before or after January 1, 2000). We excluded articles if they did not report information on reoperation, rupture, or adhesions. We used unadjusted pooled meta-analysis to report the incidence of complications, and meta-regression to describe the potential contributory factors for each complication while controlling for age, gender, and zone of injury. RESULTS: Unadjusted meta-analysis revealed rates of re-operation of 6%, rupture of 4%, and adhesions of 4%. Meta-regression analysis of 29 studies showed that core suture technique or use of an epitendinous suture does not influence rupture. However, the presence of an epitendinous suture decreases re-operation by 84%. Adhesion development is 57% lower when the modified Kessler technique is used. The incidence of complications did not vary with publication date. CONCLUSIONS: The published literature supports use of the modified Kessler repair technique with an epitendinous suture to minimize complications. Although complication rates are low, our data suggest that there has been no definitive improvement in reported complications before and after 2000.

Callus mineralization and maturation are delayed during fracture healing in interleukin-6 knockout mice.

IL-6 is a pleiotropic cytokine involved in cell signaling in the musculoskeletal system, but its role in bone healing remains uncertain. The purpose of this study was to examine the role of IL-6 in fracture healing. Eight-week-old male C57BL/6 and IL-6 -/- mice were subjected to transverse, mid-diaphyseal osteotomies on the right femora. Sacrifice time points were 1, 2, 4, or 6 weeks post-fracture (N=14 per group). Callus tissue properties was analyzed by microcomputed tomography (micro-CT) and Fourier transform infrared imaging spectroscopy (FT-IRIS). Cartilage and collagen content, and osteoclast density were measured histologically. In intact unfractured bone, IL-6 -/- mice had reduced crystallinity, mineral/matrix ratio, tissue mineral density (TMD), and bone volume fraction (BVF) compared to wildtype mice. This suggests that there was an underlying deficit in baseline bone quality in IL-6 -/- mice. At 2 weeks post-fracture, the callus of IL-6 -/- mice had reduced crystallinity and mineral/matrix ratio. These changes were less evident at 4 weeks. At 2 weeks, the callus of the IL-6 -/- mice had an increased tissue mineral density (TMD), an increased cartilage and collagen content, and reduced osteoclast density compared to these parameters in wildtype mice. By 4 and 6 weeks, these parameters were no longer different between the two strains of mice. In conclusion, IL-6 -/- mice had delayed callus maturity, mineralization, and remodeling compared with the callus of the wildtype mice. These effects were transient indicating that the role of IL-6 appears to be most important in the early stages of fracture healing.