Is the femoral component flexion affected by the sagittal femoral shaft bowing in conventional intramedullary guided TKA?

Background The aim of the present study was to investigate the influence of sagittal femoral bowing on sagittal femoral component alignment, and whether there was correlation between sagittal femoral component alignment and coronal femoral component alignment. Methods We retrospectively reviewed 77 knees in 71 patients who had undergone primary TKA for advanced osteoarthritis. All surgeries were performed by using a standard medial parapatellar approach. The osteotomy was performed with a conventional technique using an intramedullary rod for the femur and a mechanical extramedullary guiding system for the tibia. All patients enrolled in the study were evaluated with full-length lower extremity load-bearing standing scanograms, and the patients had preoperative and postoperative radiographs of the knees. Coronal femoral bowing angle (cFBA), sagittal femoral bowing angle (sFBA), and postoperatively, mechanical tibiofemoral angle of the knee (mTFA), β angle (femoral component flexion angle) were measured. The radiographic results of both groups were compared using Student's t test. A two-sided Pearson correlation coefficient was obtained to identify the correlations between FBA in the coronal and sagittal planes, as well as FBA and age or BMI, sFBA and β angle, cFBA and mTFA. Comparison of FSB incidence between different genders was made using Chi-square test. The p value < 0.05 indicates a statistically significant difference. Results The mean sFBA, cFBA, β angle, mTFA were 9.34° ± 3.56°(range 1°–16°), 3.25° ± 3.79°(range − 7° to −17°), 3.91° ± 3.15°(range − 1° to −13°), 0.60° ± 1.95°(range − 3° to −6°), respectively. There was no correlation between age and sFBA (CC = 0.192, p = 0.194) or cFBA (CC = 0.192, p = 0.194); similarly, there was no correlation between age and sFBA (CC = 0.067, p = 0.565) or cFBA (CC = 0.069, p = 0.549). The sFBA was correlated with cFBA and β angle (CC = 0.540, p < 0.01; CC = 0.543, p < 0.01, respectively), and the cFBA was correlated with mTFA (CC = 0.430, p < 0.01). There was no significant difference (p = 0.247) of cFBA between the patients with sFSB and the patients without sFSB. Conclusions The current study showed that the sFBA was correlated with cFBA in the patients undergoing TKA and the patients with sFSB usually presented non-cFSB. We also found that sFSB could affect the femoral component alignment in the sagittal plane and cFSB could affect the femoral component alignment in the coronal plane. The sFBA or cFBA was not correlated with age, BMI, or gender.

Differences in the setting of acetabular component alignment guides between the supine and lateral positions for total hip arthroplasty

The acetabular component orientation in total hip arthroplasty is of critical importance to clinical results. Although navigation systems and surgical robots have been introduced, most surgeons still use acetabular component alignment guides. This study aimed to compare the accuracy between modern acetabular component alignment guides for the lateral position and those for the supine position. Thirteen alignment guides for the lateral position and 10 for the supine position were investigated. All the lateral position alignment guides indicated cup alignment in operative definition, and the supine position alignment guides indicated cup alignment in radiographic definition. For lateral position alignment guides, the anteversion actually indicated by the alignment guide itself was smaller than that indicated by the manufacturer by a mean of 6° (maximum, 9°), and the inclination actually indicated by alignment guides themselves was larger than that by the manufacturer (p < 0.01) by a mean of 2° (maximum, 4°). For supine position alignment guides, the inclination and anteversion indicated by the alignment guide itself were identical with those indicated by the manufacturer. The current study showed that the angles actually indicated and those stated by manufacturers were not identical for lateral position alignment guides.

Is the Femoral Component Flexion Affected by the Sagittal Femoral Shaft Bowing in Conventional Intramedually Guided TKA?

Background: The aim of the present study was to investigate the influence of sagittal femoral bowing on sagittal femoral component alignment, and whether there was correlation between sagittal femoral component alignment and coronal femoral component alignment.Methods: We retrospectively reviewed 77 knees in 71 patients who had undergone primary TKA for advanced osteoarthritis.All surgeries were performed by using a standard medial parapatellar approach. The osteotomy was performed with a conventional technique using an intramedullar rod for the femur and a mechanical extramedullar guiding system for the tibia. All patients enrolled in the study were evaluated with full-length lower extremity load-bearing standing scanograms and the patients had preoperative and postoperative radiographs of the knees. cFBA(coronal femoral bowing angle), sFBA(sagittal femoral bowing angle),and postoperatively, mTFA(mechanical tibiofemoral angle of the knee), β angle(femoral component flexion angle) were measured. The radiographic results of both groups were compared using Student's t test. A two-sided Pearson correlation coefficient was obtained to identify the correlations between FBA in the coronal and sagittal planes, as well as FBA and age or BMI, sFBA and β angle, cFBA and mTFA. Comparison of FSB incidence between different genders was using chi-square test. The p value <0.05 indicates a statistically significant difference.Results: The mean sFBA, cFBA, β angle, mTFA were 9.34°±3.56°(range 1°-16°), 3.25°±3.79°(range -7°-17°), 3.91°±3.15°(range -1°-13°), 0.60°±1.95°(range -3°-6°), respectively. There was no correlation between age and sFBA(CC=0.192, p=0.194) or cFBA(CC=0.192, p=0.194), similarly, there was no correlation between age and sFBA(CC=0.067, p=0.565) or cFBA(CC=0.069, p=0.549). The sFBA was correlated with cFBA and β angle(CC=0.540, p<0.01; CC=0.543, p<0.01; respectively) and the cFBA was correlated with mTFA(CC=0.430, p<0.01). There was no significant difference(p=0.247) of cFBA between the patients with sFSB and the patients without sFSB. Conclusions: The current study showed that the sFBA was correlated with cFBA in the patients undergoing TKA and the patients with sFSB usually presented non-cFSB. We also found that sFSB could affect the femoral component alignment in the sagittal plane and cFSB could affect the femoral component alignment in the coronal plane. The sFBA or cFBA was not correlated with age, BMI or gender.

Should we abandon the patient-specific instrumentation ship in total knee arthroplasty? Not quite yet!

Patient-specific Instrumentation (PSI) is an innovative technique aiding the precise implementation of the preoperative plan during total knee arthroplasty (TKA) by using patient-specific guides and cutting blocks. Despite of the theoretical advantages, studies have reported contradictory results, thus there is no consensus regarding the overall effectiveness of PSI. Through the critical assessment of a meta-analysis published lately, this correspondence aims to highlight the complexity of comparing the efficacy of PSI to standard instrumentation (SI). The accuracy of component alignment, patient-reported outcome measures (PROMs), surgery time, blood loss, transfusion rate, and postoperative complications are commonly used outcomes for investigating the efficacy of PSI-aided TKA. By assessing component alignment, the expertise of the surgeon(s) should be taken into consideration, since PSI may not provide benefits for expert surgeons but might improve accuracy and patient safety during the learning curve of novice surgeons. With respect to PROMs and postoperative complications, PSI may not improve short-term results; however, long-term follow up data is missing. Regarding transfusion rates, favorable trends can be observed, but further studies utilizing recent data are needed for a clear conclusion. When assessing surgery time, we suggest focusing on operating room turnover instead of procedure time.

The Accuracy and Clinical Success of Robotic-Assisted Total Knee Arthroplasty

Background: Robotic-assisted total knee arthroplasty (rTKA) has emerged as a patient-specific customizable tool that enables 3-dimensional preoperative planning, intraoperative adjustment, robotic-assisted bone preparation, and soft-tissue protection. Haptic rTKA may enhance component positioning, but only a few small studies have examined patient satisfaction and clinical outcomes after haptic rTKA. Purpose: In patients who underwent haptic rTKA, we sought to evaluate (1) the discrepancy in alignment between the executed surgical plan and implanted alignment in the coronal and sagittal planes 1 year postoperatively and (2) patient-reported outcomes 2 years postoperatively. Methods: From a prospectively collected database, we reviewed 105 patients who underwent haptic rTKA from August 2016 to May 2017. Two fellowship-trained arthroplasty surgeons independently reviewed hip-to-ankle standing biplanar radiographs to measure overall limb alignment and individual tibial and femoral component alignment relative to the mechanical axis and compared this to the executed surgical plan. Patient-reported outcomes were collected preoperatively and at 2 years postoperatively using the Lower Activity Extremity Score (LEAS), Knee Injury and Osteoarthritis Outcome Score Junior (KOOS Jr.), and Numeric Pain Rating Scale (NPRS). Results: Mean patient age was 62.4 years, and mean body mass index was 30.6 kg/m2. Interobserver reliability was significant with a κ of 0.89. Absolute mean deviations in postoperative coronal alignment compared to intraoperative alignment were 0.625° ± 0.70° and 0.45° ± 0.50° for the tibia and femur, respectively. Absolute mean deviations in postoperative tibial sagittal alignment were 0.47° ± 0.76°. Overall mechanical alignment was 0.97° ± 1.79°. Outcomes in LEAS, KOOS Jr., and NPRS changed from 8 to 10, 78 to 88.3, and 8 to 1, respectively. Conclusions: Haptic rTKA demonstrated high reliability and accuracy (less than 1°) of tibial coronal, femoral coronal, and tibial sagittal component alignment postoperatively compared to the surgical plan. Patient-reported outcomes improved, as well. A more rigorous study on long-term outcomes is warranted.

Comparison with Navigation of a Novel Three-Step Technique for Improving Accuracy of the Distal Femoral Resection during Conventional TKA: A Case–Control Study

Correct placement of the femoral component in the coronal plane during primary total knee arthroplasty (TKA) is related to long-term survival. The aim of this radiographic study was to determine the accuracy of a novel three-step technique for improving the accuracy of the distal femoral cut during conventional technique and compare it with computer navigation during TKA. A total of 458 TKAs were retrospectively analyzed (178 conventional TKAs with the novel technique and 280 navigated TKAs) for postoperative femoral component coronal alignment and compared between the two groups. Mean femoral component coronal alignment was not significantly different (p = 0.314) between the two groups. There was no significant difference in the mean femoral component coronal alignment between varus and valgus knees. The number of outliers (90 ± 3 degrees) for femoral component coronal alignment was not significantly different between the two groups when assessed separately for varus and valgus deformities. The mean value of femoral component alignment using the conventional technique in knees with varus deformity <10 degrees was 88.8 degrees, in knees with varus deformity 10 to 20 degrees was 89.4 degrees, and in those with varus deformity >20 degrees was 90.2 degrees. Femoral component alignment in knees with varus <10 degrees was significantly different from those >20 degrees (p = 0.006); there was no significant difference between knees with varus <10 degrees and those with 10 to 20 degrees varus (p = 0.251), nor between 10 and 20 degrees varus knees and those with varus >20 degrees (p = 0.116). Using the novel three-step technique during conventional TKA to perform the distal femoral cut can help achieve femoral component coronal alignment comparable to the navigation technique.

Retraction Note: Effect of sagittal femoral component alignment on biomechanics after mobile-bearing total knee arthroplasty

This article has been retracted. Please see the Retraction Notice for more detail: https://doi.org/10.1186/s13018-019-1458-5.