Faculty Bibliography

BACKGROUND:Periacetabular osteotomy (PAO) has been used as a treatment modality for development dysplasia of the hip (DDH). Many patients will progress to total hip arthroplasty (THA) following PAO. There is a discrepancy in the literature regarding outcomes of THA after PAO. METHODS:A retrospective study was performed. Ten pa- tients (12 hips) with prior PAO who progressed to THA with at least 1-year follow-up after THA were identified. A control group of patients matched for age, sex, and body mass index (BMI) who underwent primary THA with minimum of 1-year follow-up were included. Demographic and radiographic parameters as well as clinical outcomes using the modified Harris Hip Score (mHHS) were collected. RESULTS:The mean age at the time of THA was 36.2 ± 9.7 years for the PAO and 37.8 ± 9.1 years for the control cohorts. There was no difference in the demographics be- tween the groups. At mean follow-up time of 22.8 ± 10.7 months for the PAO group and 25 ± 13.8 months for the control group, there was no significant difference in mHHS following THA. There was significant improvement in mHHS from preoperative to postoperative levels (p < 0.01). CONCLUSION/CONCLUSIONS:Total hip arthroplasty is an effective means to restore quality of life and function in patients who develop osteoarthritis following PAO, with equivalent outcomes to those undergoing primary THA.

BACKGROUND:The objective of this study was to investigate the impact of alignment and soft tissue release on patient outcomes following total knee arthroplasty (TKA). METHODS:In a multicenter study, soft tissue releases during TKA were prospectively documented in 330 robotic-assisted TKAs. Knee Injury and Osteoarthritis Outcome Scores (KOOS) were captured postoperatively. Delphi analysis was used to determine inlier and outlier component alignment boundaries: Tibia Coronal (TC): ±3°, Femur Coronal (FC): ±3°, Femoral Axial (FA): 3°Int-6°Ext, Hip-Knee-Ankle (HKA): 3°Val-4°Var, and Tibiofemoral Axial (TFA): 3°Int-6°Ext. Kruskal-Wallis analysis of variance tests were used to compare groups. RESULTS:No significant differences were found between any individual or grouped inlier and outlier alignment criterion and KOOS at any timepoint. Outlier alignment frequencies were: TC: 0%, FC: 12%, FA: 8%, HKA: 9%, TFA: 8%, and Any: 23%. Soft tissue releases were performed in 18% of cases. Knees with soft tissue releases reported significantly worse KOOS scores at: 6M: Symptoms (80.0 versus 75.3, P = .03), activities of daily living (ADL) (86.2 versus 80.8, P = .030), quality of life (70.1 versus 60.9, P = .008), 12M ADL (90.0 versus 85.1, P = .023), and 24M ADL (91.9 versus 87.2, P = .016). A higher proportion of patients achieved Minimal Clinically Important Difference for pain at 6 months for those having no releases versus released (92.3% versus 81.0%, P = .021). No significant associations were found between preoperative deformity and preoperative or postoperative KOOS. CONCLUSION/CONCLUSIONS:After trying to balance the TKA with bony cuts alone, the addition of soft tissue releases after bony cuts is associated with worse KOOS scores out to 2 years and was more prevalent in knees with worse deformity, whereas no such association was found for alignment.

BACKGROUND:Frequently, patients indicated for total hip arthroplasty (THA) present with low back pain (LBP) and hip pain. The purpose of this study was to compare patients whose back pain resolved after THA with those where back pain did not resolve and identify how to predict this using spinopelvic parameters. METHODS:We reviewed a series of 500 patients who underwent THA for unilateral hip osteoarthritis by 2 surgeons. Patients underwent biplanar standing and sitting EOS radiographs pre-operatively. Patients with previous spine surgery or femoral neck fracture were excluded. Demographic data was analyzed at baseline. The Oswestry Disability Index (ODI) scores were calculated pre-operatively and at 1 year postoperatively. Spinopelvic parameters included, pelvic incidence and sacral slope (SS) change from standing to sitting. RESULTS:Two hundred and four patients (41%) had documented LBP before THA. The Oswestry Disability Index (ODI) for patients improved from 38.9 ± 17.8 pre-operatively to 17.0 ± 10.6 at 1 year post-operatively (P < .001). At 1- and 2-year follow-up, resolution of back pain occurred in 168 (82.4%) and 187 (91.2%) patients, respectively. Pelvic incidence was not predictive of back pain resolution. All patients whose back pain resolved had a sacral slope change from standing to sitting of >10°, while those patients whose back pain did not resolve had a change of <10°. CONCLUSION/CONCLUSIONS:This study demonstrates that symptomatic low back pain (LBP) resolves in 82% of patients after THA. The results of this study may be used to counsel patients on back pain and its resolution following total hip replacement.

BACKGROUND:Targets of acetabular inclination and anteversion have been suggested based on a patient's spinopelvic mobility. Current methods in total hip arthroplasty (THA) include manual instrumentation, computer-assisted navigation, and robotic-assisted surgery. This study aims to compare the accuracy of these 3 methods in targeting the functional safe zone. METHODS:This is a prospective multicenter study including a series of 251 consecutive primary posterior THA patients from April 2019 to January 2021. Preoperative lateral standing and sitting spinopelvic radiographs were obtained. Each patient was classified using the Hip-Spine Classification. A functional safe zone plan was determined. Surgeons used their preferred method (manual instrumentation, computer-assisted, or robotic-assisted). Postoperative anteversion and inclination was measured and compared to the preoperative plan. Mean differences between preoperative and postoperative values were calculated. Welch's t-test was used to assess significant between-group differences with P < .05 considered significant. RESULTS:Of the 249 patients, there were 63 manual instrumentation, 68 computer-assisted navigation, and 118 robotic-assisted surgery. Robotic-assisted surgery (rTHA) was significantly more accurate in targeting anteversion (1 ± 2) compared to manual instrumentation (mTHA; 7 ± 6, P < .001) and computer-assisted navigation (cTHA; 6 ± 6, P < .001). rTHA was also significantly more accurate in targeting inclination (1 ± 1) compared to mTHA (8 ± 7, P < .001) and cTHA (6 ± 7, P < .001). Although cTHA had greater accuracy in targeting both inclination and anteversion compared to mTHA, these differences were not statistically significant. CONCLUSION/CONCLUSIONS:Robotic-assisted surgery was more accurate than both computer-assisted navigation and manual instrumentation in targeting the functional safe zone in primary THA. Further research is needed to evaluate the effect of improved accuracy on dislocation rates.

Purpose/UNASSIGNED:Computer navigation in total hip arthroplasty (THA) offers potential for more accurate placement of acetabular components, avoiding impingement, edge loading, and dislocation, all of which can necessitate revision THA (rTHA). Therefore, the use of computer navigation may be particularly beneficial in patients undergoing rTHA. The purpose of this study was to determine if the use of computer-assisted hip navigation reduces the rate of dislocation in patients undergoing rTHA. Methods/UNASSIGNED:A retrospective review of 72 patients undergoing computer-navigated rTHA between February 2016 and May 2017 was performed. Demographics, indications for revision, type of procedure performed, and incidence of postoperative dislocation were collected for all patients. Clinical follow-up was recorded at 3 months, 1 year and 2 years. Results/UNASSIGNED: < 0.05). Conclusion/UNASSIGNED:Our study demonstrates a significant reduction in dislocation rate following rTHA with computer navigation. Although the cause of postoperative dislocation is often multifactorial, the use of computer navigation may help to curtail femoral and acetabular malalignment in rTHA. Level of Evidence/UNASSIGNED:Level III: retrospective.

AIMS/OBJECTIVE:Navigation devices are designed to improve a surgeon's accuracy in positioning the acetabular and femoral components in total hip arthroplasty (THA). The purpose of this study was to both evaluate the accuracy of an optical computer-assisted surgery (CAS) navigation system and determine whether preoperative spinopelvic mobility (categorized as hypermobile, normal, or stiff) increased the risk of acetabular component placement error. METHODS:< 10°) spinopelvic mobility contributed to increased error rates. RESULTS:The paired absolute difference between CAS and postoperative imaging measurements was 2.3° (standard deviation (SD) 2.6°) for inclination and 3.1° (SD 4.2°) for anteversion. Using a target zone of 40° (± 10°) (inclination) and 20° (± 10°) (anteversion), postoperative standing radiographs measured 96% of acetabular components within the target zone for both inclination and anteversion. Multiple logistic regression analysis controlling for BMI and sex revealed that hypermobile spinopelvic mobility significantly increased error rates for anteversion (odds ratio (OR) 2.48, p = 0.009) and inclination (OR 2.44, p = 0.016), whereas stiff spinopelvic mobility increased error rates for anteversion (OR 1.97, p = 0.028). There were no dislocations at a minimum three-year follow-up. CONCLUSION/CONCLUSIONS: 2022;3(6):475-484.

Component alignment in total knee arthroplasty is a determining factor for implant longevity. Mechanical alignment, which provides balanced load transfer, is the most common alignment strategy. However, a retrospective review found that varus alignment, which could lead to unbalanced loading, can happen in up to 18% of tibial baseplates. This may be particularly burdensome for cementless tibial baseplates, which require low bone-implant micromotion and avoidance of bone overload to obtain bone ingrowth. Our aim was to assess the effect of varus alignment on the bone-implant interaction of cementless baseplates. We virtually implanted 11 patients with knee OA with a modern cementless tibial baseplate in mechanical alignment and in 2° of tibial varus alignment. We performed finite element simulations throughout gait, with loading conditions derived from literature. Throughout the stance phase, varus alignment had greater micromotion and percentage of bone volume at risk of failure than mechanical alignment. At mid-stance, when the most critical conditions occurred, the average increase in peak micromotion and amount of bone at risk of failure due to varus alignment were 79% and 59%, respectively. Varus alignment also resulted in the decrease of the surface area with micromotion compatible with bone ingrowth. However, for both alignments, this surface area was larger than the average area of ingrowth reported for well-fixed implants retrieved post-mortem. Our findings suggest that small varus deviations from mechanical alignment can adversely impact the biomechanics of the bone-implant interaction for cementless tibial baseplates during gait; however, the clinical implications of such changes remain unclear.

AIMS/OBJECTIVE:Spinopelvic mobility plays an important role in functional acetabular component position following total hip arthroplasty (THA). The primary aim of this study was to determine if spinopelvic hypermobility persists or resolves following THA. Our second aim was to identify patient demographic or radiological factors associated with hypermobility and resolution of hypermobility after THA. METHODS:) ≥ 30°. Radiological spinopelvic parameters, including SS, pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, anterior pelvic plane tilt (APPt), and spinopelvic tilt (SPT), were measured on preoperative imaging, and at six weeks and a minimum of one year postoperatively. The severity of bilateral hip osteoarthritis (OA) was graded using Kellgren-Lawrence criteria. RESULTS:increased from baseline (11.4° (SD 8.8°)) to one year after THA by 11.5° (SD 7.4°) (p < 0.001), which correlates to an 8.5° (SD 5.5°) mean decrease in seated functional cup anteversion. Contralateral hip OA was the only radiological predictor of hypermobility persisting at one year after surgery. The overall reoperation rate was 1.5%. CONCLUSION/CONCLUSIONS: 2021;103-B(12):1766-1773.

BACKGROUND:Imageless computer navigation improves component placement accuracy in total hip arthroplasty (THA), but variations in the registration process are known to impact final accuracy measurements. We sought to evaluate the registration accuracy of an imageless navigation device during THA performed in the lateral decubitus position. METHODS:A prospective, observational study of 94 patients undergoing a primary THA with imageless navigation assistance was conducted. Patient position was registered using 4 planes of reference: the patient's coronal plane (standard method), the long axis of the surgical table (longitudinal plane), the lumbosacral spine (lumbosacral plane), and the plane intersecting the greater trochanter and glenoid fossa (hip-shoulder plane). Navigation measurements of cup position for each plane were compared to measurements from postoperative radiographs. RESULTS:Mean inclination from radiographs (41.5° ± 5.6°) did not differ significantly from inclination using the coronal plane (40.9° ± 3.9°, P = .39), the hip-shoulder plane (42.4° ± 4.7°, P = .26), or the longitudinal plane (41.2° ± 4.3°, P = .66). Inclination measured using the lumbosacral plane (45.8° ± 4.3°) differed significantly from radiographic measurements (P < .0001). Anteversion measured from radiographs (mean: 26.1° ± 5.4°) did not differ significantly from the hip-shoulder plane (26.6° ± 5.2°, P = .50). All other planes differed significantly from radiographs: coronal (22.6° ± 6.8°, P = .001), lumbosacral (32.5° ± 6.4°, P < .0001), and longitudinal (23.7° ± 5.2°, P < .0001). CONCLUSION/CONCLUSIONS:Patient registration using any plane approximating the long axis of the body provided a frame of reference that accurately measured intraoperative cup position. Registration using a plane approximating the hip-shoulder axis, however, provided the most accurate and consistent measurement of acetabular component position.

CASE:A 69-year-old woman underwent revision total knee arthroplasty for patellar component aseptic loosening. The periprosthetic tissue demonstrated histologic features of an adaptive immune response (aseptic lymphocyte-dominant vasculitis-associated lesion [ALVAL]). No particles of corrosion debris were identified. The inflammation seemed to be associated with zirconium oxide (ZrO2) particles added as a bone cement radio-opacifier. CONCLUSION:The factors responsible for the adaptive immune response cannot be determined with certainty; however, this is the first reported case of ALVAL associated with ZrO2-containing bone cement. Previous reports describing ALVAL around failed total knee prostheses have not included observations about the type of contrast material added to cement.