Sagittal mechanical ratio: A novel technique to define sagittal alignment of the femur independent of distal anatomic landmarks.

BACKGROUND: Radiographic measurements to study sagittal alignment in the setting of knee are frequently difficult to evaluate due the presence of a prosthesis or implant that obscures traditional radiographic landmarks. In this paper we present a novel method of determining sagittal femoral alignment in the presence of obscuring implants. METHODS: 98 full-length femoral radiographs were reviewed and divided into two groups. In Group 1, the Distal Mechanical Point (DMP) was used to calculate the Distal Mechanical Ratio (DMR), defined as the ratio of the linear distance from the DMP to the anterior cortical axis divided by the distance from the anterior cortical axis to posterior condylar cortex. In group 2, the sagittal mechanical axis was measured using the true DMP (tDMP) and then separately measured using the DMR to find the calculated DMP (cDMP), and the angular variance between the calculated (cSMA) and true (tSMA) sagittal mechanical axis was calculated, as well as the linear distance between the tDMP and cDMP. Twenty additional patients with knee replacements were then selected and two observers used a cSMA to determine a femoral prosthesis flexion angle (FPFA), with intraobserver correlation calculated. RESULTS: The mean DMR was found to be 0.24, with high intraobserver correlation and normal distribution. Validation of the model demonstrated angular variance between tSMA and cSMA less than 1 degree and linear distance between tDMP and cDMP less than 1 mm. Calculation of cCMA in the presence of total knee arthroplasty revealed very strong intraobserver correlation of 0.89. CONCLUSION: The Distal Mechanical Ratio reliably predicted the true Sagittal Mechanical Axis within 1 degree and true Distal Mechanical Point within 1 mm, indicating that it may be a valuable tool for evaluating sagittal femoral alignment in cases where anatomic landmarks may be absent or obscured.

Role of inflammatory markers in the preoperative evaluation of patients undergoing salvage total hip arthroplasty.

Surgeons may use laboratory tests, including erythrocyte sedimentation rate, C-reactive protein (CRP), and white blood cell count, as well as joint aspirations to diagnose prosthetic joint infections. There is a paucity of literature correlating preoperative inflammatory markers with risk of infection in the setting of salvage total hip arthroplasty (THA). This retrospective case analysis included patients who underwent a THA salvage procedure a minimum of 3 months after a failed fixation of a proximal femur or acetabulum, with a goal of assessing the utility of inflammatory markers as a screening tool in preoperative evaluation of salvage THA. Eighty-five patients met inclusion criteria. Thirteen patients were diagnosed with an infection preoperatively or intraoperatively during salvage THA. An elevated preoperative CRP level was a significant marker for infection. A CRP of 7.1 produced 80% sensitivity, 88% specificity, and a receiver operating characteristic curve of 0.840. There was a high rate of perioperative complications (17.6%) in salvage THA regardless of the presence of infection. In conclusion, CRP levels are useful in the preoperative evaluation for periprosthetic joint infection before salvage THA.

Incision site fat thickness and 90-day complications for direct anterior and posterior approach total hip arthroplasty.

BACKGROUND: Defining the distribution of subcutaneous fat around the hip in relation to different approaches for total hip arthroplasty (THA) may lead to a better understanding of the relationship between obesity and complications. The purpose of this study was to: (1) describe the intraoperative thickness of subcutaneous fat at the incision site for direct anterior (DAA) and posterior approaches (PA) for THA; and (2) examine the relationship between fat thickness and 90-day postoperative complications. METHODS: Intraoperative fat measurements were obtained at the anterior incision site (AT-IS) of the DAA (n = 60) and the lateral incision site (LT-IS) of the PA (n = 64). Lateral hip fat thickness was measured from preoperative anteroposterior pelvis radiographs (LT-XR). Body mass index (BMI), sex, age, and 90-day complications were collected retrospectively. RESULTS: Patients within the same demographic groupings had significantly more fat laterally than anteriorly, between 9.6 mm and 17.96 mm. Return to the OR was significantly associated with BMI, AT-IS, and LT-IS. Wound complications were significantly associated with AT-IS. Periprosthetic joint infection (PJI) was significantly associated with BMI and LT-IS. No outcome variables were associated with LT-XR, approach, sex, or age. LT-XR was strongly correlated with AT-IS and LT-IS. CONCLUSIONS: Regardless of BMI, sex, or age more soft tissue was encountered with a PA compared to a DAA. General adiposity was associated with return to the OR. Excess incisional fat was associated with wound complications following a DAA and PJI after a PA. LT-XR and clinical examination near the proposed incision, may provide helpful data in making preoperative risk assessments.

Clinical Pathways of Patients Denied Total Knee Arthroplasty Due to an Institutional BMI Cutoff.

Out of concern for the increased risk of complications with morbid obesity, institutional body mass index (BMI) cutoffs for total knee arthroplasty (TKA) have become commonplace. We sought to answer the questions: what percentage of morbidly obese patients with knee osteoarthritis who present to an arthroplasty clinic will, within 2 years, undergo TKA at (1) a BMI less than 40 kg/m2 or (2) at a BMI greater than 40 kg/m2? Of those who do not undergo surgery, (3) what percentage lose enough weight to become TKA-eligible, and (4) what percentage do not? We performed an observational study of 288 patients, of which 256 had complete follow-up. Institutional electronic medical record review and patient follow-up by telephone were conducted to determine which patients underwent surgery, and at what BMI. For those that did not undergo TKA, BMI was examined to see if the patient ever lost enough weight to become TKA eligible. Twelve of 256 patients (4.7%) underwent TKA at a BMI less than 40 kg/m2, 64 patients (25%) underwent TKA at a BMI greater than 40 kg/m2, and 7 patients (2.7%) underwent surgery at an outside hospital. The average BMI at the time of surgery was 42.3 kg/m2. Thirty-seven of 256 patients (14.4%) lost enough weight to become TKA-eligible within 2 years of the initial visit but did not undergo surgery, while 136 patients (53.1%) neither underwent TKA nor became eligible. Strict enforcement of a BMI cutoff for TKA is variable among surgeons. In the absence of weight loss protocols, 19.1% of morbidly obese patients may be expected to reach the sub-40 kg/m2 BMI milestone.

Predictive value of lateral soft tissue thickness for complications after total hip arthroplasty with a lateral incision.

The purpose of this study was to determine the relationship between soft tissue thickness lateral to the greater trochanter, as measured on anteroposterior pelvis radiograph, and postoperative complications following primary total hip arthroplasty. A retrospective review of 1110 consecutive patients treated at a single institution from 2003 to 2011 was conducted. Postoperative complications were divided into surgical site infections, deep wound infections, noninfectious surgical complications, need for revision surgery, and medical complications. Lateral soft tissue thickness (LSTT) was measured as the horizontal distance from the most lateral point on the greater trochanter to the skin edge obtained from anteroposterior hip radiographs. Among the 1110 study patients, 19.19% had a postoperative complication, with a deep infection rate of 3.42%. Of the previously identified risk factors, increased LSTT and body mass index were both associated with surgical site infection and deep infection, and LSTT was associated with revision surgery. An LSTT value of >5 cm was predictive of surgical site infection, deep infection, and revision surgery. This easily obtainable radiographic measurement, along with clinical examination near the operative site, might prove helpful in making preoperative risk assessments.

Dry Needling Versus Cortisone Injection in the Treatment of Greater Trochanteric Pain Syndrome: A Noninferiority Randomized Clinical Trial.

Study Design Prospective, randomized, partially blinded. Background Greater trochanteric pain syndrome (GTPS) is the current terminology for what was once called greater trochanteric or subgluteal bursitis. Cortisone (corticosteroid) injection into the lateral hip has traditionally been the accepted treatment for this condition; however, the effectiveness of injecting the bursa with steroids is increasingly being questioned. An equally effective treatment with fewer adverse side effects would be beneficial. Objective To investigate whether administration of dry needling (DN) is noninferior to cortisone injection in reducing lateral hip pain and improving function in patients with GTPS. Methods Forty-three participants (50 hips observed), all with GTPS, were randomly assigned to a group receiving cortisone injection or DN. Treatments were administered over 6 weeks, and clinical outcomes were collected at baseline and at 1, 3, and 6 weeks. The primary outcome measure was the numeric pain-rating scale (0-10). The secondary outcome measure was the Patient-Specific Functional Scale (0-10). Medication intake for pain was collected as a tertiary outcome. Results Baseline characteristics were similar between groups. A noninferiority test for a repeated-measures design for pain and averaged function scores at 6 weeks (with a noninferiority margin of 1.5 for both outcomes) indicated noninferiority of DN versus cortisone injection (both, P<.01). Medication usage (P = .74) was not different between groups at the same time point. No adverse side effects were reported. Conclusion Cortisone injections for GTPS did not provide greater pain relief or reduction in functional limitations than DN. Our data suggest that DN is a noninferior treatment alternative to cortisone injections in this patient population. Level of Evidence Therapy, level 1b. Registered December 2, 2015 at www.clinicaltrials.gov (NCT02639039). J Orthop Sports Phys Ther 2017;47(4):232-239. Epub 3 Mar 2017. doi:10.2519/jospt.2017.6994.

Distribution of Subcutaneous Fat Around the Hip in Relation to Surgical Approach for Total Hip Arthroplasty.

BACKGROUND: Although preoperative risk assessment is multifactorial, subcutaneous fat thickness at the incision site has been associated with postoperative complications in studies of total hip arthroplasty (THA) and other procedures. This study compared subcutaneous fat thickness encountered in THA approaches using a lateral hip incision with that of approaches using an anterior incision and examined the relationship between body mass index (BMI) and fat distribution based on sex and age. METHODS: Subcutaneous fat measurements were obtained from 2004 patient CT images at positions that correspond with lateral and anterior incision sites for common approaches to THA. A thickness ratio (lateral/anterior) was calculated, and BMI, sex, and age were collected via chart review. RESULTS: Males and females had significantly different thickness ratio averages at 1.97 and 2.68, respectively. Thickness ratios were not significantly different between BMI groups. Lateral thickness averages were significantly different for males and females, and the interaction between sex and BMI group was significant. The relationship between BMI and the thickness ratio in males aged ≥65 years was significantly different from males of <65 years and females of all ages. CONCLUSION: Regardless of BMI, sex, or age, incision site soft tissue thickness was greater for approaches using a lateral hip incision than for those with an anterior incision, and a positive relationship between BMI and both measurements was identified. The predominance of lateral fat was more pronounced in females of all age and BMI groups and less pronounced in obese males aged ≥65 years.

Plateau-patella angle in evaluation of patellar height after total knee arthroplasty.

The plateau-patella angle (PPA) has been proposed as a new and simpler method to describe patellar height. This method has not been used or validated in knees following total knee arthroplasty (TKA). A modified PPA (mPPA) was developed for use in this population. The method was validated by determining the interobserver and intraobserver reliability of the technique in 50 consecutive patients compared to three well-described methods of describing patellar height after TKA. Three observers then evaluated the mPPA of 297 post-operative radiographs to describe a normal range after TKA for a given technique and implant. The interobserver reliability was the highest for the mPPA compared to the other methods. The mean mPPA for the entire cohort was 21.06, 20.49, and 19.94 for the three observers. The modified plateau-patella angle is a reliable way to evaluate patellar height in patients who have undergone total knee arthroplasty.

Acetabular cartilage thickness: accuracy of three-dimensional reconstructions from multidetector CT arthrograms in a cadaver study.

PURPOSE: To prospectively quantify the accuracy of hip cartilage thickness estimated from three-dimensional (3D) surfaces, generated by segmenting multidetector computed tomographic (CT) arthrograms by using direct physical measurements of cartilage thickness as the reference standard. MATERIALS AND METHODS: Four fresh-frozen cadaver hip joints from two male donors, ages 43 and 46 years, were obtained; institutional review board approval for cadaver research was also obtained. Sixteen holes were drilled perpendicular to the cartilage of four cadaveric acetabula (two specimens). Hip capsules were surgically closed, injected with contrast material, and scanned by using multidetector CT. After scanning, 5.3-mmcores were harvested concentrically at each drill hole and cartilage thickness was measured with a microscope. Cartilage was reconstructed in 3D by using commercial software. Segmentations were repeated by two authors. Reconstructed cartilage thickness was determined by using a published algorithm. Bland-Altman plots and linear regression were used to assess accuracy. Repeatability was quantified by using the coefficient of variation, intraclass correlation coefficient (ICC), repeatability coefficient, and percentage variability. RESULTS: Cartilage was reconstructed to a bias of -0.13 mm and a repeatability coefficient of + or - 0.46 mm. Regression of the scatterplots indicated a tendency for multidetector CT to overestimate thickness. Intra- and interobserver repeatability were very good. For intraobserver correlation, the coefficient of variation was 14.80%, the ICC was 0.88, the repeatability coefficient was 0.55 mm, and the percentage variability was 11.77%. For interobserver correlation, the coefficient of variation was 13.47%, the ICC was 0.90, the repeatability coefficient was 0.52 mm, and the percentage variability was 11.63%. CONCLUSION: Assuming that an accuracy of approximately + or - 0.5 mm is sufficient, reconstructions of cartilage geometry from multidetector CT arthrographic data could be used as a preoperative surgical planning tool.