Tom Schmidt-Braekling

Minimal invasive posterior total hip arthroplasty: are 6 weeks of hip precautions really necessary?

IntroductionPostoperative hip dislocations have been reported in 0.5 to 10.6xa0% of patients after primary posterolateral total hip arthroplasty (THA). Hip precautions are currently recommended for 6xa0weeks postoperatively to reduce early dislocation and facilitate healing of the posterior soft tissue repair.Materials and methodsTo determine the impact of a modified 4-week precaution protocol on the dislocation rate, 698 consecutive patients (797 hips) operated by a single surgeon between September 2008 and December 2012 were retrospectively evaluated. All patients had a standard THA using a minimal invasive posterior approach with posterior soft tissue repair and 28–36-mm head size. 98.7xa0% of the patients were available for follow-up.ResultsThere were eight (1xa0%) dislocations in 797 hips in the first 12xa0months after surgery with 4xa0weeks of hip precautions. The average time to dislocation was 7.5xa0weeks after surgery (range 1.0–16.9xa0weeks); two dislocations (25xa0%) took place in the first 4xa0weeks.ConclusionsShortening the time of posterolateral hip precautions from 6 to 4xa0weeks after surgery does not increase the risk of postoperative dislocation.

Silver-coated megaprostheses: review of the literature

Periprosthetic infection remains one of the most serious complications following megaendoprostheses. Despite a large number of preventive measures that have been introduced in recent years, it has not been possible to further reduce the rate of periprosthetic infection. With regard to metallic modification of implants, silver in particular has been regarded as highly promising, since silver particles combine a high degree of antimicrobial activity with a low level of human toxicity. This review provides an overview of the history of the use of silver as an antimicrobial agent, its mechanism of action, and its clinical application in the field of megaendoprosthetics. The benefits of silver-coated prostheses could not be confirmed until now. However, a large number of retrospective studies suggest that the rate of periprosthetic infections could be reduced by using silver-coated megaprostheses.

Does stem design influence component positioning in total hip arthroplasty using a minimal invasive posterolateral approach

PurposeLimited data exist for the reconstructive potential of short bone-preserving stems in THA using a minimal invasive posterolateral approach. Our study aim was to assess the effect of stem design on the reconstruction of hip offset and leg length in MIS posterolateral THA.MethodsThis retrospective consecutive single-surgeon study compares hip offset and leg length, as well as acetabular component positioning (cup anteversion; inclination) of 129 THAs with a cementless standard-length stem (Synergy®) and 143 THAs with a cementless short bone-preserving stem (Trilock®).ResultsIn reference to the contralateral side, the mean difference in hip offset was 0.9xa0mm (pu2009=u20090.067) for the standard stem and 0.1xa0mm (pu2009=u20090.793) for the short stem, respectively. Leg-length discrepancy was 0.7xa0mm (Synergy®) and 0.9xa0mm (Trilock®), respectively. A total of 233 (86xa0%) acetabular components fell within the target zone for anteversion and inclination.ConclusionAccurate component positioning in MIS posterolateral approach THA is possible and is not influenced by the type of stem.

Does the tibia component design affect the need for offset stems in revision total knee arthroplasty

IntroductionThe stem/keel location varies between anatomic and symmetric revision tibial baseplates. The current study investigates the impact of an anatomic versus symmetric stem location on the need for offset couplers in revision total knee arthroplasty.Materials and methodsHip to ankle standing radiographs and lateral radiographs of 75 patients were analyzed using digital templating software. The offset in the anterior–posterior as well as medial–lateral plane between the center of the tibial diaphysis and the stem of the tibial baseplate were determined for an anatomic and symmetric tibial baseplate, respectively. Measurements were repeated for 4 resection levels: tip of fibular head (0), 10xa0mm (1), 15xa0mm (2) and 20xa0mm (3) below the tip of the fibula head.ResultsAnatomic tibial baseplates require less offset for resection levels up to the tip of the fibula: total offset 2.28 versus 5.44xa0mm (pu2009<u20090.001). However, for defects that result in resection levels below the tip of the fibula symmetric tibial baseplates require less offset: resection level 1: 3.18 versus 2.4xa0mm (pu2009=u20090.008), 2: 4.81 versus 1.67xa0mm (pu2009<u20090.001) and resection level 3: 5.66 versus 1.52xa0mm (Pu2009<u20090.001).ConclusionThe current study suggests that while asymmetric anatomic tibial baseplates have benefits for revisions with minimal bone loss, symmetric tibial baseplates require less offset when larger bone defects are encountered.

Cobalt serum levels differ in well functioning Birmingham resurfacing and Birmingham modular THA

IntroductionMetal-on-metal (MoM) bearings are known to release metal ions secondary to wear and corrosion. This may cause local reactions (adverse soft tissue reactions and osteolysis) and systemic effects. Little is known about the exact pattern and the differences between large head MoM total hip replacements (THA) and resurfacings (HR).Questions(1) Is there a difference in metal ion concentrations between HR and MoM-THR using the same bearing design (Birmingham Hip Resurfacing System, Smith & Nephew, Inc. Memphis, TN, USA)? (2) Are metal ion levels changing over time in MoM-THA or HR? (3) Do acetabular inclination angle and femoral component size influence cobalt and chromium levels? Is there a correlation between clinical outcome and metal ion levels?Materials and methodsA retrospective analysis was conducted in 77 well functioning unilateral Birmingham HR and 42 well functioning unilateral modular Birmingham MoM-THA (Smith & Nephew, Inc. Memphis, TN, USA) operated on between 2007 and 2012. Blood samples were taken at a minimum of 13xa0months and subsequent during annual follow-ups.Results(1) Cobalt levels were significantly higher in MoM-THA compared to HR (pxa0<xa00.001). There was no significant difference in chromium levels (pxa0=xa00.313). (2) Cobalt is increasing over time in MoM-THA (pxa0=xa00.030) whereas metal ions remain stable in HR. (3) Metal ion levels were not affected by acetabular inclination angle and femoral component size in MoM-THA. Chromium levels correlate with the femoral component size (rxa0=xa0−0.240; pxa0=xa00.037), the UCLA activity score (rxa0=xa0−0.344; pxa0=xa00.003) and the VAS (rxa0=xa00.263; pxa0=xa00.38) in HR.ConclusionConsidering that HR and MoM-THA used the same MoM bearing design, increased cobalt levels may be related to trunnion wear or corrosion. Elevated cobalt levels should raise concern for corrosion related failure in MoM-THA.

Imaging of ceramic liner fractures in total hip arthroplasty: the value of CT.

Fracture of a ceramic liner of a total hip arthroplasty is rare and is radiographically occult if not displaced. We report on two patients in whom ceramic liner fracture was radiographically occult but was diagnosed on subsequent CT scan through appropriate windowing.

Ultrasound and fluoroscopy are unnecessary for injections into the arthritic hip

PurposeWe investigated the effectiveness of non-image-guided hip injections.MethodsWe retrospectively evaluated 369 intra-articular hip injections in 331 patients using anatomical landmarks. The percentage and duration of pain relief was documented. Hip injections were grouped in responders and nonresponders (50xa0% maximum pain relief as a cut off).ResultsIn 82% (nu2009=u2009304) of hip injections, patients responded positively and experienced >50xa0% pain relief. Nonresponders had a significantly higher body mass index (pu2009=u20090.007).ConclusionsHip injections using anatomical landmarks are an effective treatment option for patients with osteoarthritis of the hip.

Assessment of the lateral patellar facet in varus arthritis of the knee

BACKGROUNDnLateral patellar arthritis has been associated with poor outcomes in unicompartmental knee arthroplasty. The current study correlates intraoperative findings with MRI imaging, skyline radiographs and the presence of anterior knee pain.nnnMETHODSnIn 92 consecutive knees with varus arthritis, the patellofemoral compartment was assessed during surgery, on skyline radiographs and on MRI. Anterior knee pain was recorded on a visual-analog-scale. Intraoperative assessment was based on the Outerbridge grading scale. Skyline radiographs were evaluated according to the Ahlbäck grading scale; MRIs were assessed according to a modified Outerbridge grading scale.nnnRESULTSnThere was an excellent correlation (rs=0.833; p<0.001) in the cartilage assessment of the lateral patellar facet between MRI and surgery. A good correlation (rs=0.664; p<0.001) was seen between Ahlbäck Grades and macroscopic Outerbridge Grades of the lateral patella. Ahlbäck Grades and MRI modified Outerbridge Grades showed a good correlation (rs=0.643; p<0.001) for the lateral patella. Twelve percent of knees (seven out of 60) with Ahlbäck Grade 0 or 1 and mild to moderate anterior knee pain had a macroscopic Outerbridge Grade of 3 on the lateral patella. None of these 60 knees had a full-thickness cartilage defect on MRI.nnnCONCLUSIONnNormal skyline radiographs in patients with mild to moderate anterior knee pain can rule out full-thickness cartilage defects of the lateral patellar facet as observed during surgery and on MRI. The MRI allows for the most accurate assessment of the patellofemoral joint and is warranted in all patients with radiographic abnormalities or severe anterior knee pain.nnnLEVEL OF EVIDENCEnDiagnostic study, Level II.

Do Changes in the Production Process Affect the Outcome of Ceramic Liners: A 3-Year Follow-Up Study

BACKGROUNDnIn 2011, the current liner was withdrawn from the market because of the potential risk for liner fracture secondary to increased pressures used to assemble the metal locking ring. The present study provides a short-term follow-up of patients with this implant.nnnMETHODSnWe retrospectively evaluated 63 consecutive hips in 53 patients operated by a single surgeon using a recalled ceramic-on-ceramic bearing. There were 30 women and 23 men with an average age of 50.6 years (range 20.3-63.5 years). The mean follow-up was 36.8 months.nnnRESULTSnSix hips in 6 patients were revised (9.5%) because of a liner-fracture during the follow-up period. All liner fractures were identified on computer tomography imaging. Nine patients had self-reported episodes of squeaking (14.3%). All 6 patients that underwent revision surgery for liner fracture described squeaking before revision. There were no revisions for other causes. Two of the revised patients had a subsequent dislocation (33%).nnnCONCLUSIONnThe recalled ceramic liner lots have an increased liner fracture rate. Patients with mechanical symptoms or squeaking should undergo computer tomography to rule out liner facture.

The Rule of Histology in the Diagnosis of Periprosthetic Infection: Specific Granulocyte Counting Methods and New Immunohistologic Staining Techniques may Increase the Diagnostic Value.

Objective: To estimate the extent to which psychophysical quantitative sensory test (QST) and patient factors (gender, age and comorbidity) predict pain, function and health status in people with shoulder disorders. To determine if there are gender differences for QST measures in current perception threshold (CPT), vibration threshold (VT) and pressure pain (PP) threshold and tolerance. Design: A cross-sectional study design. Setting: MacHAND Clinical Research Lab at McMaster University. Subjects: 34 surgical and 10 nonsurgical participants with shoulder pain were recruited. Method: Participants completed the following patient reported outcomes: pain (Numeric Pain Rating, Pain Catastrophizing Scale, Shoulder Pain and Disability Index) and health status (Short Form-12). Participants completed QST at 4 standardized locations and then an upper extremity performance-based endurance test (FIT-HaNSA). Pearson r’s were computed to determine the relationships between QST variables and patient factors with either pain, function or health status. Eight regression models were built to analysis QST’s and patient factors separately as predictors of either pain, function or health status. An independent sample t-test was done to evaluate the gender effect on QST. Results: Greater PP threshold and PP tolerance was significantly correlated with higher shoulder functional performance on the FIT-HANSA (r =0.31-0.44) and lower self-reported shoulder disability (r = -0.32 to -0.36). Higher comorbidity was consistently correlated (r =0.31-0.46) with more pain, and less function and health status. Older age was correlated to more pain intensity and less function (r =0.31-0.57). In multivariate models, patient factors contributed significantly to pain, function or health status models (r2 =0.19-0.36); whereas QST did not. QST was significantly different between males and females [in PP threshold (3.9 vs. 6.2, p < .001) and PP tolerance (7.6 vs. 2.6, p < .001) and CPT (1.6 vs. 2.3, p =.02)]. Conclusion: Psychophysical dimensions and patient factors (gender, age and comorbidity) affect self-reported and performance-based outcome measures in people with shoulder disorders.