Pelvic pitch and roll during total hip arthroplasty performed through a posterolateral approach. A potential source of error in free-hand cup positioning.

PURPOSE: Intraoperative pelvic motion can alter the perceived cup inclination and version during non-navigated THA. We quantified pelvic motion during different phases of primary THA performed in the lateral decubitus through a posterolateral approach. METHODS: Pelvic roll (rotation of the coronal plane) and pitch angles (rotation parallel to the coronal plane) were studied in 75 patients undergoing THA for osteoarthritis by four arthroplasty surgeons. Ten steps of surgery were defined. Angular motion was recorded with a miniature surgical device that utilizes inertial sensors. RESULTS: The mean absolute roll ranged from 0.03° detected at the end of surgery to 4.13° detected during acetabular exposure. The mean absolute pitch ranged from 0.05° detected at the end of surgery to 2.54° detected during hip dislocation. The maximum pelvic roll and pitch detected during surgery averaged 17.62° (SD: 5.08) and 9.3° (SD: 3.39) respectively. Absolute roll and pitch angles were not affected by patient's BMI, sex, pre-operative hip motion, or surgeon. Before cup insertion, the greatest mean change in roll was observed during acetabular exposure (10.02° anteriorly), and for pitch was observed during dislocation (1.88° caudally). CONCLUSION: During THA performed through a posterolateral approach, there is a progressive anterior pelvic roll that peaks before cup insertion. This can lead to underestimation of cup anteversion during non-navigated THA. The anterior roll does not completely correct, even when all retractors and external forces acting on the pelvis are removed. Pelvic pitch that could affect the perceived cup inclination occurs to a lesser extent than pelvic roll.

Sustained neurochemical plasticity in central terminals of mouse DRG neurons following colitis.

Sensitization of dorsal root ganglia (DRG) neurons is an important mechanism underlying the expression of chronic abdominal pain caused by intestinal inflammation. Most studies have focused on changes in the peripheral terminals of DRG neurons in the inflamed intestine but recent evidence suggests that the sprouting of central nerve terminals in the dorsal horn is also important. Therefore, we examine the time course and reversibility of changes in the distribution of immunoreactivity for substance P (SP), a marker of the central terminals of DRG neurons, in the spinal cord during and following dextran sulphate sodium (DSS)-induced colitis in mice. Acute and chronic treatment with DSS significantly increased SP immunoreactivity in thoracic and lumbosacral spinal cord segments. This increase developed over several weeks and was evident in both the superficial laminae of the dorsal horn and in lamina X. These increases persisted for 5 weeks following cessation of both the acute and chronic models. The increase in SP immunoreactivity was not observed in segments of the cervical spinal cord, which were not innervated by the axons of colonic afferent neurons. DRG neurons dissociated following acute DSS-colitis exhibited increased neurite sprouting compared with neurons dissociated from control mice. These data suggest significant colitis-induced enhancements in neuropeptide expression in DRG neuron central terminals. Such neurotransmitter plasticity persists beyond the period of active inflammation and might contribute to a sustained increase in nociceptive signaling following the resolution of inflammation.

Validation of a Novel Software Measurement Tool for Total Hip Arthroplasty.

Background Preoperative planning and postoperative evaluation of component position in total hip arthroplasty (THA) utilize specialized software that must be able to provide measurements that are both accurate and precise. A new software program for use in THA has recently been developed. We sought to evaluate the accuracy of this new software in comparison with two current, widely used software programs. Methodology Postoperative anteroposterior (AP) pelvic radiographs from 135 THA patients were retrospectively reviewed. Reference values for acetabular anteversion, inclination, and leg length were established using validated software programs (TraumaCad® as the primary reference value [PRV] and OsiriX LiteTM as the secondary reference value [SRV]). Measurements from the new software program (Intellijoint VIEWTM) were compared with reference values using Student's t-test and chi-square test. Results For anteversion, mean values for the PRV (27.34° ± 7.27°) and the new software (27.29° ± 7.21°) were not significantly different (p = 0.49). The new software differed from the PRV by a mean of 0.05° ± 0.93°. Similar results were noted for inclination, where the new software differed from the PRV and SRV by -0.13° ± 0.65° and 0.25° ± 1.26°, respectively (mean values: PRV: 43.62° ± 6.02°; SRV: 43.99° ± 6.27°; new software: 43.74° ± 6.17°; p = 0.87), and for leg length, where the new software differed from the PRV and SRV by 0.05 mm ± 0.46 mm and 0.22 mm ± 0.52 mm, respectively (mean values: PRV: 10.61 mm ± 11.60 mm; SRV: 10.77 mm ± 11.70 mm; new software: 10.56 mm - ± 11.61 mm; p = 0.98). Measurements were highly correlated across multiple reviewers (intraclass correlation coefficient ≥0.987). Conclusions The new software measurement tool is accurate and precise for assessing the acetabular component position and leg length measurements following THA in AP pelvic radiographs compared to currently used image measurement software.

Surgical Approach and Reaming Depth Influence the Direction and Magnitude of Acetabular Center of Rotation Changes During Total Hip Arthroplasty.

BACKGROUND: Changes in acetabular or hip center of rotation (HCOR) commonly occur during acetabular component preparation during total hip arthroplasty (THA). HCOR displacement in mediolateral or superoinferior directions is known to influence offset and leg length, but the incidence and range of HCOR change in the anteroposterior direction is less understood as the sagittal plane cannot be measured on standard anteroposterior radiographs. This study assessed the 3-dimensional displacement of HCOR after cup implantation and evaluated for potential factors associated with increased acetabular component translations. METHODS: A total of 894 THAs were performed using a posterior, lateral, or direct anterior approach. Only intraoperative data from the navigation device were included in the analysis. All THAs performed between September 2015 and October 2017 were included. Paired t -tests were used to compare native HCOR and new HCOR values. RESULTS: The mean HCOR displacement in 3 directions was 4.97mm medially (P < .001), 0.83mm superiorly (P < .001), and 0.64mm posteriorly (P < .001). Subgroup analysis revealed greater posterior HCOR displacement with the anterior approach than the lateral/posterior approach (2.32mm vs 0.44mm; P < .001). Increasing medial HCOR displacement also resulted in increased superior and posterior HCOR displacement across surgical cases (P < .001). CONCLUSIONS: HCOR displacement is commonly observed in medial, superior, and posterior directions. HCOR changes are influenced by surgical approach, potentially secondary to patient positioning, with greater posterior HCOR displacement observed in anterior cases. Surgeons should be aware of these factors, particularly in cases with deficient or reduced posterior column bone stock.

Accuracy of Acetabular Component Positioning Using Computer-assisted Navigation in Direct Anterior Total Hip Arthroplasty.

Background  Appropriate component positioning in total hip arthroplasty (THA) is imperative for long-term survivorship. C-arm fluoroscopy provides visual guidance in the direct anterior approach (DAA), but it is limited by qualitative properties. Conversely, imageless computer-assisted navigation systems (CAS) provide surgeons with intraoperative, three-dimensional (3D) quantitative measurements for cup position, although the accuracy of such systems has not been extensively addressed in the DAA. We evaluated the ability of an imageless CAS to deliver measurements for acetabular cup position with accuracy in the DAA. Materials and methods  A retrospective analysis of 69 primary THA procedures was conducted. Acetabular cup position measurements (anteversion and inclination) obtained intraoperatively by imageless navigation were compared to standard, postoperative anteroposterior pelvic radiographic measurements. Statistical comparisons were made using the Bland-Altman technique. Results  The mean difference between device and radiographic measurements for anteversion was 3.4° (standard deviation (SD): 4.1°; absolute mean difference (ABS): 4.2°), and 4.0° for inclination (SD: 3.6°; ABS: 4.3°). Bland-Altman analysis demonstrated excellent agreement; 93% (64/69) and 97% (67/69) of anteversion pairings fell within the statistical and clinical limits of agreement, whereas 94% (65/69) and 100% (69/69) of inclination pairings were within the statistical and clinical limits, respectively. Conclusions  Measurements obtained intraoperatively for acetabular cup position using imageless navigation in the DAA are agreeable with the current clinical standard.

Computer-assisted Navigation in Hip Resurfacing Arthroplasty: A Case Study utilizing the ReCap Femoral Resurfacing System.

INTRODUCTION: The ReCap Femoral Resurfacing System has been associated with increased cases of revision surgery when compared to other hip resurfacing systems. However, computer-assisted navigation may have the potential to reduce the risk of post-operative complications by providing more accurate intraoperative measurements for acetabular component positioning. CASE REPORT: The present case describes an active 46-year-old male presenting with severe osteoarthritis of the right hip who elected to undergo a ReCap resurfacing arthroplasty with navigation. Results demonstrated accurate acetabular component position and leg length measurements to within <1° and 1mm of standard radiographic measurements. CONCLUSION: These findings are the first to describe the use of navigation with the ReCap system and provide encouraging results for further clinical evaluation.

Computer-assisted navigation in Birmingham hip resurfacing: A case report.

Component malpositioning during Birmingham hip resurfacing increases the risk for component wear, metallosis, component loosening, and the likelihood of dislocation and revision surgery. Computer-assisted navigation can increase the accuracy to which components are placed, and the utilization of this technology in Birmingham hip resurfacing is increasing. The present report summarizes the accuracy of acetabular component positioning in a Birmingham hip resurfacing case utilizing navigation. Intraoperative C-arm fluoroscopy following the use of the navigation tool confirmed excellent seating, positioning, and stability of the acetabular component. In addition, post-operative antero-posterior radiographs confirmed device accuracy and revealed a stable joint with no evidence of acetabular loosening or femoral fracture. Computer-assisted navigation may therefore be an effective tool to improve the accuracy of component positioning during Birmingham hip resurfacing.

A new mini-navigation tool allows accurate component placement during anterior total hip arthroplasty.

INTRODUCTION: Computer-assisted navigation systems have been explored in total hip arthroplasty (THA) to improve component positioning. While these systems traditionally rely on anterior pelvic plane registration, variances in soft tissue thickness overlying anatomical landmarks can lead to registration error, and the supine coronal plane has instead been proposed. The purpose of this study was to evaluate the accuracy of a novel navigation tool, using registration of the anterior pelvic plane or supine coronal plane during simulated anterior THA. METHODS: Measurements regarding the acetabular component position, and changes in leg length and offset were recorded. Benchtop phantoms and target measurement values commonly seen in surgery were used for analysis. Measurements for anteversion and inclination, and changes in leg length and offset were recorded by the navigation tool and compared with the known target value of the simulation. Pearson's r assessed the relationship between the measurements of the device and the known target values. RESULTS: The device accurately measured cup position and leg length measurements to within 1° and 1 mm of the known target values, respectively. Across all simulations, there was a strong, positive relationship between values obtained by the device and the known target values (r=0.99). CONCLUSION: The preliminary findings of this study suggest that the novel navigation tool tested is a potentially viable tool to improve the accuracy of component placement during THA using the anterior approach.

Birmingham Hip Resurfacing Using a Novel Mini-navigation System: A Case Report.

INTRODUCTION: Inaccurate positioning of acetabular and femoral components during Birmingham Hip Resurfacing (BHR) can lead to increased wear, edge-loading, and failure of the prosthesis, a consequence of substantial concern for young and active patients seeking long- term, post-operative survival of the joint. In turn, sizing of the acetabular component during BHR is limited by the size of the native femoral neck, and reaming of the acetabulum should be minimized to optimize the bony architecture for potential subsequent arthroplasties. Computer-assisted navigation systems (CAS) can improve the accuracy of component selection and positioning during total hip arthroplasty (THA); however, evidence for the usefulness of CAS in BHR is lacking. The present report summarizes a case of BHR performed with navigation to assist with component positioning. CASE REPORT: A 34-year-old male martial arts instructor presented with a constant and localized pain in the left hip and groin. Following the examination, the patient was diagnosed with left hip impingement and osteoarthritis. Due to his age and active lifestyle, the patient elected to undergo BHR rather than THA. The navigation tool was used to assist with acetabular reaming and to confirm final cup placement. Post- operatively, standard, anteroposterior pelvic radiographs showed a final cup position of 39.0° inclination and 24.7° anteversion, which was confirmed by the navigation tool. A pre-operative leg length differential of 3mm was measured from pre-operative radiographs; however, leg lengths were equalized following BHR. CONCLUSION: This report summarizes a case of BHR performed in a young, active patient with the assistance of a novel surgical navigation tool. The use of the navigation device allowed for more accurate acetabular preparation and component positioning, maximizing the bone-sparing characteristics of BHR.