Contemporary, non-navigation, cup orientation techniques improve accuracy and eliminate differences seen between the anterior and posterior approach in THA.

BACKGROUND: This study aimed to: (1) Determine the ability to achieve the surgeons' desired cup orientation, without navigation, using contemporary measures with the anterior- (AA) and posterior- approaches (PA); and (2) assess whether surgical approach is associated with cup orientation accuracy, as previously reported, when contemporary measures are used. METHODS: A prospective, 2-centre, multi-surgeon study of 400 THAs (200 AA; 200 PA) was performed. Intraoperative radiographs were obtained with the AA. A digital inclinometer and 3-point pelvic support were used with the PA. With the PA, intraoperative cup inclination at impaction was recorded. Radiographic inclination/anteversion (RI/RA) was measured from intraoperative radiographs (AA-only) and from postoperative radiographs for all cases. Optimum inclination/anteversion was defined as 40°/20° (±10°). The difference between intra- and postoperative orientations allowed for determination of the difference in pelvic position at impaction. RESULTS: Optimum RI and RA were achieved in 91.3% (n = 365) and 92% (n = 368) of cases respectively. Optimum cup orientation was detected in 84% of cases (n = 336). There was equivalent ability to achieve cup orientation between approaches (AA: 82.5% vs. PA: 85.5%; p = 0.41). The use of an inclinometer in the PA was associated with a smaller variability of inclination at implantation (10° vs. 14°) and counteracted the greater difference in pelvic position (4.4° vs. 2.1°) seen with the PA. CONCLUSIONS: Over 80% of cases can have optimum orientation without navigation, using simple, cheap contemporary measures. Such measures eliminate differences between approaches, related to patient position. Narrower implantation angles will further reduce variability in cup orientation achieved.

Supine versus lateral position for total hip replacement: accuracy of biomechanical reconstruction.

BACKGROUND: Restoration of normal hip anatomy and biomechanics is a key surgical goal for success in total hip arthroplasty. The aim of this study was to evaluate the influence, if any, that patient positioning in the supine and lateral decubitus positions has in achieving this goal. MATERIALS AND METHODS: A single center multi-surgeon case-matched series from a tertiary level referral center of patients undergoing primary unilateral THA for osteoarthritis between April 2018 and December 2019 was retrospectively analyzed. Patients (n = 200) were divided into two matched groups: supine (anterior approach, n = 100) and lateral decubitus (direct lateral or posterior/SuperPATH™ approaches, n = 100). Post-operative anteroposterior pelvic radiographs were analyzed using a previously validated software (SurgiMap, Nemaris Inc., USA) for parameters of reconstruction of the hip in the coronal plane; leg length discrepancy, vertical and horizontal displacement of the center of rotation, femoral offset, and total offset. RESULTS: Mean absolute leg length discrepancy in the supine group was 0.6 ± 3.3 mm (95% [CI] - 0.1 to 1.2 mm) versus 2.4 ± 3.8 mm (95% [CI] 1.6 to 3.1) in the lateral decubitus position (p < 0.001). The center of rotation was displaced medially by a mean of 3.2 ± 2.7 mm in the supine group versus 1.3 ± 4.0 mm in the lateral decubitus group (p < 0.001). For a surgical target of reconstructing both leg length and total offset within 5 mm of native anatomy, the supine group was more than twice as likely to achieve these goals with fewer outliers (OR 2.631, 95% [CI] 1.901-3.643) (76% v 30%, p < 0.001). CONCLUSION: Total hip arthroplasty through the anterior approach in the supine position is more consistent and accurate for the restoration of leg length and total offset. Further study is required to assess how this translates with outcome. LEVEL OF EVIDENCE: III-retrospective cohort study.

Retrospective cohort study on radial head replacements comparing results between smooth and porous stem designs.

BACKGROUND: When necessary, radial head integrity after a fracture can be re-created by the use of a radial head arthroplasty if the radial head is judged irreparable. The purpose of this study was to compare the clinical and radiographic outcomes of metal modular radial head replacements with a smooth vs. a porous stem. METHODS: A retrospective cohort study of radial head replacements performed in the first 4 weeks after a trauma in an adult patient at our institution between 2000 and 2014 was completed. Patients were divided into 2 groups: a porous stem group (ExploR; Biomet Orthopedics, Warsaw, IN, USA) and a smooth stem group (EVOLVE; Wright Medical Group, Memphis, TN, USA). Primary outcomes were the Disabilities of the Arm, Shoulder, and Hand and Mayo Elbow Performance Index scores. Secondary outcomes were the visual analog scale score for pain, range of motion, grip strength, and radiographic evaluations. RESULTS: Of the 80 eligible patients, 57 agreed to participate (porous stem group, 36; smooth stem group, 21). Demographic data were similar between the 2 groups. Average follow-up was 6.3 years. Average Disabilities of the Arm, Shoulder, and Hand and Mayo Elbow Performance Index scores were similar between the 2 groups. Porous implants were more prone to osteolysis (64.3% vs. 23.5%; P = .01) and were associated with a greater loss of elbow flexion (6° vs. 1°; P = .02). The porous stem group showed a tendency toward more overstuffing (24.0% vs. 5.9%; P = .21). CONCLUSION: Our results reveal that outcomes between smooth and porous stem metal modular radial head implants are equivalent. However, the smooth stem implant may represent the preferred option as it is associated with a lower rate of complications.