Riyaz H. Jinnah

Instability after total hip arthroplasty: treatment with large femoral heads vs constrained liners.

One of the most common complications after total hip arthroplasty is instability. This study reviewed the recent literature concerning the indications, contraindications, and results of recent studies using both constrained liners and large femoral heads to treat instability after total hip arthroplasty. We also report on the results of a series of 41 patients (52 hips) considered being at high risk for dislocation who were treated with large-diameter metal-on-metal bearings and who were compared with a matched group of hips treated with standard-size metal-on-polyethylene bearings. The large-diameter femoral head group had no dislocations at a minimum follow-up of 24 months, whereas the standard-size group had 2 dislocations. We support the use of large femoral heads to treat instability in a wide variety of patients because of the increased stability, decreased wear of modern metal-on-metal designs, increased range of motion, and variety of revision options.

Robotic systems in orthopaedic surgery

Robots have been used in surgery since the late 1980s. Orthopaedic surgery began to incorporate robotic technology in 1992, with the introduction of ROBODOC, for the planning and performance of total hip replacement. The use of robotic systems has subsequently increased, with promising short-term radiological outcomes when compared with traditional orthopaedic procedures. Robotic systems can be classified into two categories: autonomous and haptic (or surgeon-guided). Passive surgery systems, which represent a third type of technology, have also been adopted recently by orthopaedic surgeons. While autonomous systems have fallen out of favour, tactile systems with technological improvements have become widely used. Specifically, the use of tactile and passive robotic systems in unicompartmental knee replacement (UKR) has addressed some of the historical mechanisms of failure of non-robotic UKR. These systems assist with increasing the accuracy of the alignment of the components and produce more consistent ligament balance. Short-term improvements in clinical and radiological outcomes have increased the popularity of robot-assisted UKR. Robot-assisted orthopaedic surgery has the potential for improving surgical outcomes. We discuss the different types of robotic systems available for use in orthopaedics and consider the indication, contraindications and limitations of these technologies.

Does Computer-Assisted Surgery Improve Accuracy and Decrease the Learning Curve in Hip Resurfacing? A Radiographic Analysis

BACKGROUND Hip resurfacing is a technically demanding procedure in which accurate positioning of the femoral component is critical to the avoidance of early implant failures. The purpose of this study was to assess the accuracy of computer-assisted placement of the femoral component and to evaluate the impact of computer-assisted surgery on the learning curve associated with this procedure. METHODS The accuracy of positioning the femoral component was analyzed radiographically in hips undergoing resurfacing procedures performed by surgeons assigned to four different study groups: Group 1, in which the operations were performed with use of computer-assisted surgery by a fellowship-trained surgeon who was experienced in performing resurfacing arthroplasty (surgical experience, more than 250 hip resurfacings); Group 2, in which the operations were performed with use of computer-assisted surgery by senior residents who were inexperienced in performing resurfacing arthroplasty and who were closely supervised by faculty; Group 3, in which the operations were performed with use of conventional instruments by fellowship-trained faculty members; and Group 4, in which the operations were performed with use of computer-assisted surgery by a lesser experienced fellowship-trained faculty member (surgical experience, more than forty but less than seventy-five hip resurfacings) from Group 3. RESULTS The range of error in varus or valgus angulation that was observed for navigated procedures was 6 degrees in Group 1, 7 degrees in Group 2, and 5 degrees in Group 4. Compared with the preoperative neck-shaft angle value, the mean postoperative stem-shaft angle value increased by a mean of 4.7 degrees in Group 1, 7.2 degrees in Group 2, 6.5 degrees in Group 3, and 11.6 degrees in Group 4. When compared with the use of standard instrumentation, the use of computer-assisted surgery reduced the number of outliers and facilitated valgus insertion. CONCLUSIONS In the present study, computer-assisted surgery resulted in improved accuracy and precision in positioning the femoral component. In addition, computer-assisted surgery led to a reduction in the length of the learning curve for beginners in hip resurfacing and improved the surgeons ability to perform this procedure safely.

Achieving Accurate Ligament Balancing Using Robotic-Assisted Unicompartmental Knee Arthroplasty

Unicompartmental knee arthroplasty (UKA) allows replacement of a single compartment in patients with limited disease. However, UKA is technically challenging and relies on accurate component positioning and restoration of natural knee kinematics. This study examined the accuracy of dynamic, real-time ligament balancing using a robotic-assisted UKA system. Surgical data obtained from the computer system were prospectively collected from 51 patients (52 knees) undergoing robotic-assisted medial UKA by a single surgeon. Dynamic ligament balancing of the knee was obtained under valgus stress prior to component implantation and then compared to final ligament balance with the components in place. Ligament balancing was accurate up to 0.53 mm compared to the preoperative plan, with 83% of cases within 1 mm at 0°, 30°, 60°, 90°, and 110° of flexion. Ligamentous laxity of 1.31 ± 0.13 mm at 30° of flexion was corrected successfully to 0.78 ± 0.17 mm (P < 0.05). Robotic-assisted UKA allows accurate and precise reproduction of a surgical balance plan using dynamic, real-time soft-tissue balancing to help restore natural knee kinematics, potentially improving implant survival and functional outcomes.

Distal locking using an electromagnetic field-guided computer-based real-time system for orthopaedic trauma patients

Objectives: To compare the efficacy of distal interlocking during intramedullary nailing using a freehand technique versus an electromagnetic field real-time system (EFRTS). Design: A prospective, randomized controlled trial. Setting: Level I academic trauma center. Patients/Participants: Patients older than 18 years who sustained a femoral or tibial shaft fracture amenable to antegrade intramedullary nailing were prospectively enrolled between August 2010 and November 2011. Exclusion criteria included injuries requiring retrograde nailing and open wounds near the location of the distal interlocks (distal third of the femur, knee, or distal tibia). Intervention: Each patient had 2 distal interlocking screws placed: one using the freehand method and the other using EFRTS. Main Outcome Measurement: Techniques were compared on procedural time and number of interlocking screw misses. Two time points were measured: time 1 (time to find perfect circles/time from wand placement to drill initiation) and time 2 (drill initiation until completion of interlocking placement). Results: Twenty-four tibia and 24 femur fractures were studied. EFRTS proved faster at times 1 and 2 (P < 0.0001 and P < 0.0002) and total time (P < 0.0001). This difference was larger for junior residents, though reached statistical significance for senior residents. Senior residents were faster with the freehand technique compared with junior residents (P < 0.004), but the 2 were similar using EFRTS (P = 0.41). The number of misses was higher with free hand compared with EFRTS (P = 0.02). Conclusion: These results suggest that EFRTS is faster than the traditional freehand technique and results in fewer screw misses. Level of Evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

An Orthopedic-Hospitalist Comanaged Hip Fracture Service Reduces Inpatient Length of Stay:

Introduction: Hip fractures are common in the elderly patients with an incidence of 320 000 fractures/year in the United States, representing a health-care cost of US

Retrospective Clinical and Radiological Outcomes after Robotic Assisted Bicompartmental Knee Arthroplasty.

9 to 20 billion. Hip fracture incidence is projected to increase dramatically. Hospitals must modify clinical models to accommodate this growing burden. Comanagement strategies are reported in the literature, but few have addressed orthopedic-hospitalist models. An orthopedic-hospitalist comanagement (OHC) service was established at our hospital to manage hip fracture patients. We sought to determine whether the OHC (1) improves the efficiency of hip fracture management as measured by inpatient length of stay (LOS) and time to surgery (TTS) and (2) whether our results are comparable to those reported in hip fracture comanagement literature. Methods: A comparative retrospective–prospective cohort study of patients older than 60 years with an admitting diagnosis of hip fracture was conducted to compare inpatient LOS and TTS for hip fracture patients admitted 10 months before (n = 45) and 10 months after implementation (n = 54) of the OHC at a single academic hospital. Secondary outcome measures included percentage of patients taken to surgery within 24 or 48 hours, 30-day readmission rates, and mortality. Outcomes were compared to comanagement study results published in MEDLINE-indexed journals. Results: Patient cohort demographics and comorbidities were similar. Inpatient LOS was reduced by 1.6 days after implementation of the OHC (P = .01) without an increase in 30-day readmission rates or mortality. Time to surgery was insignificantly reduced from 27.4 to 21.9 hours (P = .27) and surgery within 48 hours increased from 86% to 96% (P = .15). Discussion: The OHC has improved efficiency of hip fracture management as judged by significant reductions in LOS with a trend toward reduced TTS at our institution. Conclusion: Orthopedic-hospitalist comanagement may represent an effective strategy to improve hip fracture management in the setting of a rapidly expanding patient population.

Fracture of a Charnley acetabular component from polyethylene wear.

Purpose. Bicompartmental knee arthroplasty (BiKA) is a favorable alternative to total knee arthroplasty for degenerative disease limited to two knee compartments. Recently developed robotic-assisted systems improved the clinical efficacy of unicompartmental knee arthroplasty by providing enhanced component positioning with dynamic ligament balancing. The purpose of this study was to evaluate the short-term outcomes of patients, undergoing bicompartmental knee arthroplasty at a single institution by a single surgeon using a robotic-assisted system. It was hypothesized that robotic assisted BiKA is a prevailing choice for degenerative disease limited to two knee compartments with good functional results. Methods. A search of the institutions joint registry was conducted to identify patients that underwent robotic-assisted BiKA of the patellofemoral compartment and the medial or lateral compartment. Results. A total number of 29 patients (30 BiKA) with a mean age of 63.6 years were identified who received a patellofemoral resurfacing in combination with medial or lateral compartment resurfacing. Twenty-four out of 29 patients had good to excellent outcome. Conclusion. Robotic assisted bicompartmental arthroplasty using broad indications and only excluding patients with severe deformity and those that have less than 4 mm of joint space in the surviving compartment demonstrated 83% good to excellent results.

Editorial on “Determination of the accuracy of navigated kinematic unicompartmental knee arthroplasty: a 2-year follow-up”

A 42-year-old man incurred a fracture of the high-density polyethylene socket eight years after a Charnley arthroplasty with a 22 mm head. The excessive wear debris resulted in severe tissue reaction and included resorption of surrounding cancellous bone stock. Polyethylene component wear, occasionally seen in total hip arthroplasties, may be relatively more common in hip replacements that do not fail from loosening.

Implementation of robotics in total joint arthroplasty

The article entitled “Determination of the accuracy of navigated kinematic unicompartmental knee arthroplasty: a 2-year follow-up” (1) published in the Journal of Arthroplasty was reviewed in detail. We would like to commend the authors on taking on such an important topic. This investigation retrospectively reviewed prospective data collected over a 4-year period on consecutive patients that underwent minimally invasive unicompartmental knee arthroplasty (UKA) with the Stryker (Mahwah, NJ, USA) Triathlon partial knee arthroplasty (PKA) prosthesis with the use of the Stryker precision computer navigation (PCN) system.