The Effect of Femoral Head Size, Neck Length, and Offset on Dislocation Rates of Constrained Acetabular Liners.

BACKGROUND: Constrained acetabular liners (CALs) are used in both primary and revision total hip arthroplasty in cases where stability and abductor deficiency are of concern. The efficacy of CALs has been shown to be design dependent. There is clear evidence that the use of small head sizes and shorter offset in unconstrained total hip arthroplasty is associated with higher rates of dislocation. To our knowledge, no such study has assessed the effect of femoral head size, neck length, and offset for CALs. METHODS: We performed a retrospective study assessing the outcomes of CALs with minimum 2-year follow-up. A Kaplan-Meier survivorship analysis was conducted for all patients and for patients revised for instability. A binomial regression analysis was performed to assess for variables significantly associated with CAL failure. RESULTS: A total of 285 CALs in 281 patients were identified with a mean follow-up of 5.7 years. Ten-year Kaplan-Meier survival analyses were as follows: all indication 91.9% vs instability 85.5% (P = .15). Increasing neck length was associated with lower rates of failure (odds ratio, 0.81; P = .042). Femoral head size, offset, and abductor reconstruction were not significantly associated with CAL failure. CONCLUSION: Larger head size has not been demonstrated to lead to lower failure in CALs. Increasing neck length was associated with lower failure rate. Surgeons should be cautious when attempting to ream to larger acetabular shell sizes for the purpose of using larger heads with CALs. Increasing neck length may instead be targeted intraoperatively.

Does Age Influence Patient-Reported Outcomes in Unilateral Primary Total Hip and Knee Arthroplasty?

BACKGROUND: Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are used to treat patients with end-stage arthritis. Previous studies have not demonstrated a consistent relationship between age and patient-reported outcomes. The purpose of this study is to assess the impact of age on patient-reported outcomes after unilateral primary THA or TKA. METHODS: A retrospective review of available data in Alberta Bone and Joint Health Institute (ABJHI) Data Repository was performed. We identified 53,498 unilateral primary THA and TKA between April 2011 and 2017. Patients were divided by age into 3 categories: <55, 55-70, and >70. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and EuroQoL 5-dimension (EQ-5D) Canada scores were obtained at presurgery, 3 and 12 months postoperatively. RESULTS: For TKA, younger patients had larger improvements in WOMAC scores at 3 and 12 months (P = <.001-.033), and in EQ-5D scores at 3 months (P < .001). When adjusted, patients <55 had lower WOMAC and EQ-5D scores at 3 months postoperatively compared to those 55-70 or >70 (all P < .01). Outcomes at 12 months did not differ between age-groups. For THA, younger patients had larger improvements in WOMAC at 3 months (P = .03). When adjusted, patients <55 had higher WOMAC scores at 12 months postoperatively compared to those 55-70 or >70, and higher EQ-5D scores compared to those 55-70 (all P < .05). CONCLUSION: While a multitude of factors go in to quantifying successful THA or TKA, this study suggests that patient age should not be a deterrent when considering the impact of age on patient-reported outcomes.

Mechanical and imaging evaluation of the effect of sutures on tendons: tape sutures are protective to suture pulling through tendon.

BACKGROUND: High-strength sutures, including #2 and tape-type, are popular when performing arthroscopic rotator cuff repair. Although the most common mechanism of anatomic failure of rotator cuff repair is suture pulling through tendon, the effect of sutures on the suture-tendon interface has rarely been investigated. We evaluated the effect of commercially available modern high-strength standard #2 and tape-type sutures on tendon. METHODS: Isolated sutures (FiberTape, #2 FiberWire [Arthrex Inc., Naples, FL, USA], Ultratape, and #2 Ultrabraid [Smith & Nephew, Andover, MA, USA]) and suture-tendon constructs using sheep infraspinatus tendons were evaluated using mechanical testing and imaging (microcomputed tomography) techniques. RESULTS: For the 4 suture-tendon constructs evaluated, maximum and residual displacements were all less than 3 mm. Whether evaluating isolated sutures or suture-tendon constructs, tape-type sutures had smaller displacements than standard #2 sutures when products from the same company were compared. On initial suture passing and after mechanical testing, hole volume was larger in constructs with tape-type rather than standard #2 sutures comparing within the same company. Collectively, constructs with larger hole volumes after mechanical testing had stiffer sutures. The percentage difference in hole volume was larger for standard #2 than tape-type sutures: FiberWire (43%), Ultrabraid (17%), FiberTape (11%), and Ultratape (9%). CONCLUSIONS: Tape-type sutures created larger final holes than standard #2 sutures from the same company. When initially passed through the tendon, tape-type sutures produced larger holes than standard #2 sutures; however, standard #2 sutures enlarged their initially smaller holes more and displaced more than tape-type sutures during cyclic loading, which suggests that tape-type sutures may be protective to suture pulling through tendon.