Nimrod Snir

Background: There is no consensus on the optimal type of antibiotic-loaded bone cement (ALBC) spacer for ue in the first stage of revision total hip arthroplasty (THA) as a method for treating/managing periprosthetic joint infection (PJI) following THA. The purpose of this study was to determine the influence of ALBC spacer type on a collection of outcome metrics for revision THA (rHA). We hypothesized that infectious complications would be comparable across spacer types, while mechanical complications would be more common with the use of hemiarthroplasty ALBC spacer designs in rHA. Methods: This was a multicenter retrospective review of 144 patients who underwent a planned two-stage revision for THA for PJI between 2011 and 2022. Patients were stratified into three groups: pre-molded articulating hemiarthroplasty ALBC (PHA) spacers, custom articulating hemiarthroplasty ALBC (CHA) spacers, and custom ALBC THA (CTHA) spacers. The types and incidence of complications that arose during the time that the spacer was in situ were obtained. In total, 29 (20.1%) PHA, 11 (7.6%) CHA, and 104 (72.2%) CTHA patients were included. Results: CHA patients were significantly younger (mean age: 54.1 years) than PHA (mean age: 63.9) and CTHA (mean age: 63.9) patients (p = 0.011). The proportion of patients discharged home was significantly higher in the CHA group (81.8%) compared to that in both the CTHA group (64.4%) and the PHA group (34.5%) (p = 0.02). The re-revision rate for hip PJI was higher for CHA (18.2%), followed by PHA (13.8%) and CTHA (5.8%), while hemiarthroplasty spacers had the highest dislocation rate (13.8% in PHA and 18.2% in CHA vs. 3.8% in CTHA, p = 0.055). The vast majority of the outcome metrics did not differ among the three spacer groups, with examples being the incidence of dislocations, the incidence of all types of unplanned procedures for treating/managing re-infection, the time to the second stage in the rHA, and the proportion of spacers that were not removed until the second stage in the rHA. Conclusions: For the vast majority of the outcome metrics determined, the difference among the three study groups was not significant. Thus, the present results suggest that antibiotic-loaded cement spacer type does not influence outcomes when a spacer is used in the first stage of a two-stage protocol for the revision of a THA.

Introduction: Instability following total hip arthroplasty (THA) remains a challenging complication. Dual-mobility (DM) hip components are aimed at improving joint stability by increasing the head-neck ratio and jump distance. However, data regarding the efficacy of these implants in the trauma setting are scarce. This study aimed to compare the dislocation rates of DM bearings with conventional THA in patients undergoing primary THA for the treatment of hip fractures. Methods: We retrospectively reviewed all patients who underwent THA for hip fractures between the years 2010–2022 and had a minimum follow-up of two years. Patient demographics and radiographic parameters, including cup version, leg length discrepancy (LLD) and femoral horizontal offset, were compared between patients who received DM bearings and patients who received conventional THA. Dislocation and revision surgery rates were also compared between the groups. Results: The study included 570 patients who met inclusion criteria, of which 82 patients were in the DM bearings group and 488 patients were in the conventional THA group. Baseline demographics and comorbidity profiles were comparable between the groups. Cup anteversion was significantly lower in the DM group (11.1° vs. 14.1°; p = 0.006), while no significant differences were observed in LLD nor femoral offset between the groups (p = 0.38, p = 0.69, respectively). Dislocation rates were similar between the DM and conventional THA groups (1.2% vs. 1.02%, respectively; p = 0.54). Furthermore, revision rates were similar between DM and conventional THA (1.22% vs. 2.87%, respectively; p = 0.387). Conclusions: While no significant differences in dislocation rates were observed between dual-mobility and conventional THA bearings, the significantly lower cup anteversion suggests a potential improvement in acetabular safe zone positioning, this could reflect a broader margin for error in implant positioning. Further prospective studies are needed to elucidate the biomechanical advantages of DM bearings in patients with hip fractures.

Introduction: The Coronal Plane Alignment of the Knee (CPAK) classification categorizes knee phenotypes based on constitutional limb alignment and joint line obliquity (JLO). Restricted Inverse Kinematic Alignment (RIKA) is a surgical philosophy that incorporates calculated perioperative parameters to achieve patient-specific alignment. This study investigated the reproducibility of restoring preoperative CPAK phenotypes via the tibia-first RIKA concept in total knee arthroplasty (TKA). Methods: This prospective study assessed 129 patients who underwent RIKA TKA using an imageless navigation robotic-assisted arm with a single implant design for primary osteoarthritis between January 2022 and December 2023. Preoperative and postoperative angles for the lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) were measured from full-length standing anteroposterior X-ray imaging. Arithmetic HKA (aHKA) was defined as MPTA - LDFA, and JLO was outlined as MPTA + LDFA to classify each knee into one of nine CPAK phenotypes. CPAK boundaries for neutral aHKA and JLO were 0° ± 2° and 180° ± 3°, respectively. Results: The mean pre- and postoperative aHKA were − 2.73° (SD ± 4.9°) vs. -2.83° (SD ± 3.0°), respectively. The most common preoperative CPAK phenotypes were I ( n = 74, 42.5%) and II ( n = 40, 23.0%). Among patients with preoperative type I phenotype, 39.2% (29/74) preserved their composition postoperatively, while 48.6% (36/74) converted to type IV. Of 40 Type II knees, 65.0% (26/40) preserved alignment, with 25.0% (10/40) shifting to type V. In preoperative types IV and V, 75% (12/16) and 88.5% (23/26) preserved their phenotypes, respectively. Valgus categories (III, VI, IX) were neutralized into types II and V. CPAK types VII, VIII, and IV were rare throughout. Conclusion: The use of tibia-first RIKA achieved adequate preservation of the native coronal alignment postoperatively. These findings suggest that balancing a knee using tibia-first approach with the use of imageless navigation robotic-assisted systems is a valid tool for surgeons who seek contemplating RIKA TKA.

Introduction: Varus or valgus knee deformities influence ankle coronal alignments. The impact of Total Knee Arthroplasty (TKA) on ankle joint alignment has not been entirely illustrated. Inverse Kinematic Alignment (iKA) is a surgical philosophy that aims to restore soft tissue balance, function, and native anatomy within validated boundaries to restore restrictive native kinematics. Therefore, this study aimed to investigate the postoperative association of patient-specific alignment on the coronal alignment of the ankle in patients with varus knee deformity who underwent iKA TKA. We hypothesized that greater preoperative varus malalignments would correlate with significant postoperative ankle coronal alignment changes. Methods: This retrospective study of a prospective collected cohort assessed patients who underwent imageless navigation assisted robotic TKA using a single implant design for primary osteoarthritis between January 2022 and August 2023. Preoperative and postoperative full-length standing anteroposterior X-ray imaging was used to measure Hip-Knee-Ankle (HKA), Tibial Plafond Inclination (TPI), Talar inclination (TI), and Tibiotalar Tilt (TTT) angles. Patients were subsequently divided into groups of neutral varus) < 10°) and severe varus (≥ 10°) according to the preoperative HKA angle. Results: Significant changes in preoperative and postoperative HKA angles were found in the severe varus (14.5° vs. 6.4°, p < 0.001) group. Changes were also significant between preoperative and postoperative TPI and TI angles in the severe varus group; however, TTT did not reach statistical significance. Delta change from pre- to postoperative HKA was significantly higher for the severe varus group (8.1° vs. 0.8°, p < 0.019). Delta change of TPI, TI and TTT did not differ between groups. Conclusion: Coronal knee alignment after TKA affects coronal alignment of the ankle. iKA technique in TKA for varus knee deformity preserves or minimizes substantial coronal alignment changes of the ankle joint. These findings may add to the benefits reported for patient specific alignment TKA techniques. Level of evidence: III.

Introduction: In total knee arthroplasty (TKA), suboptimal restoration of joint line obliquity (JLO) and joint line height (JLH) may lead to diminished implant longevity, increased risk of complications, and reduced patient reported outcomes. The primary objective of this study is to determine whether restricted kinematic alignment (rKA) leads to improved restoration of JLO and JLH compared to mechanical alignment (MA) in TKA. Materials and Methods: This retrospective study assessed patients who underwent single implant design TKA for primary osteoarthritis, either MA with manual instrumentation or rKA assisted with imageless navigation robotic arm TKA. Pre- and post-operative long standing AP X-ray imaging were used to measure JLO formed between the proximal tibial joint line and the floor. JLH was measured as the distance from the femoral articular surface to the adductor tubercle. Results: Overall, 200 patients (100 patients in each group) were included. Demographics between the two groups including age, sex, ASA, laterality, and BMI did not significantly differ. Distribution of KL osteoarthritis classification was similar between the groups. For the MA group, pre- to post-operative JLO significantly changed (2.94° vs. 2.31°, p = 0.004). No significant changes were found between pre- and post-operative JLH (40.6 mm vs. 40.6 mm, p = 0.89). For the rKA group, no significant changes were found between pre- and post-operative JLO (2.43° vs. 2.30°, p = 0.57). Additionally, no significant changes were found between pre- and post-operative JLH (41.2 mm vs. 42.4 mm, p = 0.17). Pre- to post-operative JLO alteration was five times higher in the MA group compared to the rKA group, although this comparison between groups did not reach statistical significance (p = 0.09). Conclusion: rKA-TKA results in high restoration accuracy of JLO and JLH, and demonstrates less pre- and post-operative JLO alteration compared to MA-TKA. With risen interest in joint line restoration accuracy with kinematic alignment, these findings suggest potential advantages compared to MA. Future investigation is needed to correlate between joint line restoration accuracy achieved by rKA and enhanced implant longevity, reduced risk of post-operative complications, and heightened patient satisfaction.

Ashkenazi I, et al. Clin Orthop Surg. 2024 Feb;16(1):41-48. https://doi.org/10.4055/cios23157

Background: Excellent midterm results for total hip arthroplasties (THA) with cementless, tapered porous Taperloc^® femoral stems have been reported. Reports regarding such cemented stems, however, are lacking. Objectives: To evaluate the long-term outcomes of both cemented and cementless THAs with the Taperloc femoral component. Methods: The medical records of 71 patients (76 hips), operated on between January 1991 and December 2003, who had a minimum follow-up of 10 years were available for analysis. Functional analysis was performed with the Harris hip score (HHS) questionnaire and the numerical analogue scale (NAS). Radiographic analysis was performed for subsidence, radiolucent lines and osteolysis. Results: The cohort was comprised of 47 female and 24 male patients, with a mean age of 59.7 ± 12.4 years. The mean follow-up was 17.8 ± 4.4 years. 52.6% of THAs analyzed were cementless and 47.4% were cemented. Post-operative radiographs were available for 57 surgeries. Subsidence, hypertrophic ossification, radiolucent lines and osteolysis were noted in 4 (7%), 2 (2.6%), 14 (18.4%) and 11 (14.5%) hips respectively. The average HHS score at a mean follow-up of 20.1 ± 3.9 years was 62.1 (±27.7) and the NAS score was 4.6 (±3.6). During the study period, five revision surgeries were performed due to stem-related problems, one of which was for aseptic loosening. Conclusions: Our long-term experience with the Taperloc stem, both cemented and cementless, demonstrates good outcomes, with low rates of failure. This makes this prosthesis an attractive option for THAs. Level of Evidence: IV

Ashkenazi I, et al. Clin Orthop Surg. 2023 Sep;15:e68. https://doi.org/10.4055/cios23102