Severe genu varus deformity does not affect enhanced recovery after surgery total knee arthroplasty outcomes.

INTRODUCTION: Enhanced recovery after surgery (ERAS) has been increasingly adopted in orthopaedic surgery. Although not an exclusion criterion, patients undergoing total knee arthroplasty (TKA) with preoperative severe varus deformity may be less likely to be enrolled for ERAS. This study aimed to compare the success of ERAS TKA between patients with severe preoperative varus deformities (≥ 15° varus) and the control group (< 15° varus to 14° valgus). Our secondary aim was to compare postoperative complications and functional outcomes between the two groups. MATERIALS & METHODS: 310 TKAs performed from August 2019 to February 2021 were analyzed with a follow-up of 6 months postoperatively. The primary outcome, ERAS TKA success, was defined as length of hospital stay of < 24 h. Other parameters included 30-day postoperative complications and clinical outcomes such as the original Oxford Knee Score (OKS), the Knee Society Knee (KSKS) and Function Score (KSFS), Visual Analog Scale for Pain (VAS-P), 36-Item Short-Form Health Survey (SF-36) Physical Component Summary (PCS) and SF-36 Mental Component Summary (MCS). RESULTS: There were 119 patients in the severe deformity group and 191 patients in the control group. There were no significant differences in ERAS success between the severe deformity group and control group, with both groups achieving similarly high rates (> 90%) of ERAS success. There were also no differences in 30-day postoperative complications and 6-month postoperative clinical outcomes. CONCLUSION: Patients with severe preoperative varus deformity undergoing ERAS TKA achieved high ERAS success rates (> 90%). Genu varum is not a contraindication for ERAS TKA.

Factors influencing correction rate following hemiepiphysiodesis using tension band plates for deformities around the knee: a multivariate analysis study.

PURPOSE: The aim of this study was to appraise various factors influencing the correction rate in temporary hemiepiphysiodesis (THE) around the knee joint. Specifically, the study analysed the relationship of correction rate with age, gender, aetiology, type and location of deformity. METHODS: The retrospective study included children who underwent THE for a coronal plane deformity (genu valgus or varum) around the knee joint (distal femur or proximal tibia) over a ten year period (2010-2020). The primary outcome of interest was the correction rate of the deformity. RESULTS: Thirty-three children (27 females and 6 males) with a mean age of 8.1 years involving 86 plates were included in the study. The mean correction achieved was 12.2° over a treatment period of 13.3 months. Subgroup analysis showed significant differences between the type (varus (0.8° per month), valgus (1.1° per month)) and the location of deformity femur (1.2° per month) and tibia (0.7° per month)]. On multivariate analysis, the location and the duration of treatment showed significant associations with the correction rate. CONCLUSION: The correction of coronal deformities following temporary hemiepiphysiodesis is influenced by several factors. Valgus, femoral and deformities in younger children correct at a faster rate. Location of deformity and duration of treatment emerged as potential factors affecting the correction rate.

Effect of tibial rotation after uniplane medial open-wedge high tibial osteotomy in genu varum patients: An observational study.

The change in axial tibial rotation after uniplane medial open-wedge high tibial osteotomy (uniplane OWHTO) and its relevant influence factor is not known. Therefore, the aim of this study was to evaluate the change in axial tibial rotation after uniplane OWHTO, and the factors affecting tibia rotational change were analyzed. Between January 2022 and April 2022, the study was retrospectively conducted on genu varum patients who underwent uniplane OWHTO. In the weight-bearing anteroposterior long leg view, the hip-knee-ankle angle and medial proximal tibial angle (MPTA) were evaluated. The posterior tibial slope were measured from the lateral view. A CT scan of the knee joint was performed to evaluate the distal tibial rotation angle (TRA), femorotibial rotation angle and tibial tuberosity-trochlear groove distance. In addition, the foot morphology was assessed by the ankle deformity angle and ankle rotation angle using an angle measuring instrument. All parameters were measured preoperatively and 14 days after surgery. The mean change in hip-knee-ankle, MPTA was 10.5°±2.9°, 8.8°±2.6°. The mean preoperative and postoperative TRA were 25.1°±6.9° and 22.2°±6.2° respectively (P = .007). Thus, the mean ∆TRA was -3.0°±3.4° (IR) with a range of -9.6° to +2.8° after surgery. No significant differences were found in the femorotibial rotation angle and tibial tuberosity-trochlear groove distance before and after surgery (P > .05). The postoperative ankle rotation angle and ankle deformity angle changed significantly compared with preoperative values (P < .001). In the multiple regression analysis, ∆MPTA was the only predictor of distal tibial rotation (ß = 0.667, P = .003). The current study confirms an unintended internal rotation in the distal tibia following uniplane MOWHTO and the rotation in the distal tibia was influenced by the opening width. Surgeron should keep in mind to avoid the osteotomy complication leading to excessive rotation change during surgery.

MAKO robot-assisted total knee arthroplasty cannot reduce the aggravation of ankle varus incongruence after genu varus correction ≥ 10°: a radiographic assessment.

INTRODUCTION: The objective of this study was to investigate the ankle alignment alterations after the correction of knee varus deformity in MAKO robot-assisted total knee arthroplasty (MA-TKA). METHODS: A retrospective analysis was conducted for 108 patients with TKA from February 2021 to February 2022. Patients were divided into two groups based on MAKO robot involvement during the procedure: the MA-TKA group (n = 36) and the conventional manual total knee arthroplasty (CM-TKA) group (n = 72). The patients were divided into four subgroups according to the degree of surgical correction of the knee varus deformity. Seven radiological measurements were evaluated pre and post-surgery: mechanical tibiofemoral angle (mTFA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), lateral distal tibial angle (LDTA), tibial plafond inclination angle (TPIA), talar inclination angle (TIA), and tibiotalar tilt angle (TTTA). TTTA is a quantitative representation of the extent of ankle incongruence. RESULTS: The number of mTFA, mLDFA, and MPTA outliers in the MA-TKA group was significantly lower compared to the CM-TKA group (P<0.05). Knee varus deformity was properly corrected and the mechanical axis was restored in all patients, regardless of the treatment group. Only for varus corrections ≥ 10° did TTTA change significantly (p < 0.01) and ankle varus incongruence aggravate post-operation. The ΔTTTA correlated negatively with ΔTFA (r=-0.310,P = 0.001) and correlated positively with ΔTPIA (r = 0.490,P = 0.000). When the varus correction was ≥ 7.55°, the probability of ankle varus incongruence exacerbation increased 4.86-fold. CONCLUSION: Compared with CM-TKA, MA-TKA osteotomy showed more precision but was unable to reduce post-operation ankle varus incongruence. When the varus correction ≥ 10°, ankle varus incongruence aggravated, while when the varus correction ≥ 7.55°, the probability of ankle varus incongruence increased 4.86-fold. This may occasion the pathogenesis of ankle pain following TKA.

High tibial osteotomy for acute correction and subsequent gradual tensioning of the posterolateral knee ligament complex in treating genu varum combined with a lateral thrust using the Ilizarov technique in adults: surgical technique and early results.

OBJECTIVE: To report the early results of using the Ilizarov technique in performing medial wedge opening high tibial osteotomy (MWOHTO) combined with gradual tensioning of the posterolateral corner in adult patients presenting with genu varum (GV) and lateral thrust. METHODS: A prospective case series study included 12 adult patients with a mean age of 25.2 ± 8.1 years who presented with GV deformity associated with lateral thrust. They were evaluated clinically using the "hospital for special surgery" (HSS) knee scoring system. Radiological evaluation was performed using long film from hip to knee to ankle (HKA) radiographs; the overall mechanical alignment was measured as the HKA angle, the upper tibial deformity was measured as the medial proximal tibial angle (MPTA), and the joint line convergence angle (JLCA) was measured. Surgical technique included using Ilizarov for MWOHTO below the level of the tibial tubercle, acute correction of the GV deformity, fibular osteotomy, and gradual distalization of the proximal fibula. RESULTS: After a mean follow-up of 26.3 ± 6.4 months, all osteotomies were united. All patients achieved fibular osteotomy site bony union except two with a fibrous union. The HSS score showed improvement from a mean preoperative score of 88.7 ± 7.6 to a postoperative 97.3 ± 3.9 (P < 0.05). The overall mechanical lower limb alignment improved significantly from a mean preoperative HKA of 164.5 ± 3.2 to a postoperative 178.9 ± 1.6 (P < 0.05). The MPTA improved significantly from 74.6 ± 4.1 to 88.9 ± 2.3, as well as the JLCA from 12.17 ± 1.9 to 2.3 ± 1.7 (P < 0.05). Grade 1 pin tract infection was developed in four patients and was treated conservatively. In two patients, mild pain over the fibular osteotomy site was relieved over time. The lateral thrust reoccurred at the last follow-up evaluation in the two poliomyelitis patients. CONCLUSION: MWOHTO, concomitant with tensioning the knee lateral soft tissue structure at the same setting through applying an Ilizarov apparatus, showed promising functional and radiological outcomes.

Hemiepiphysiodesis for Lower Extremity Coronal Plane Angular Correction in the Distal Femur and Proximal Tibia in Children With Achondroplasia.

BACKGROUND: Achondroplasia is the most prevalent form of skeletal dysplasia, affecting more than 250,000 individuals. Lower extremity angular deformities, particularly genu varum, are common in children with achondroplasia, often resulting in pain and limitation of function. The authors aim to determine the utility of lower extremity growth modulation with hemiepiphysiodesis in children with achondroplasia for correction of coronal plane deformities about the knee. METHODS: The authors performed a retrospective chart review of a single center from 1/1/2000 to 12/31/2020 to identify pediatric patients with achondroplasia treated with hemiepiphysiodesis as their initial procedure at the distal femur and/or proximal tibia. Patients with adequate records and who had completed their treatment were included. Data collected included duration of treatment, complications, need for osteotomy, and radiographic measurements including initial and final mechanical axis deviation, knee mechanical axis zone, mechanical lateral distal femoral angle and medial proximal tibia angle. RESULTS: Ten patients with 17 limbs met our criteria. Nine patients (15 limbs) were treated for genu varum and 1 patient (2 limbs) was treated for genu valgum. Prior to treatment, the mechanical axis fell in zone 3 in 59% of limbs and zone 2 in 41%. Average correction in mechanical axis deviation was 26.1 mm. Average change in mechanical lateral distal femoral angle was 10.3 degrees per limb, and average change in medial proximal tibia angle was 7.1 degrees per limb. Average treatment duration was 909 days. At final follow up, 81% (14/17) of limbs had the mechanical axis in zone 1, with the remaining 18% (3/17) in zone 2. No patient/limb underwent subsequent distal femur or proximal tibia osteotomy for coronal plane alignment. CONCLUSIONS: Children with achondroplasia can successfully be treated with hemiepiphysiodesis to correct coronal plane deformities at the distal femur and proximal tibia. Using this technique, no patient in our series required an osteotomy for genu varum/valgum. LEVEL OF EVIDENCE: Therapeutic level IV, Case series.

Femoral bowing affects varus femoral alignment but not patient satisfaction in mechanically aligned total knee arthroplasty.

PURPOSE: This study evaluated whether patients with particular lower limb morphological factors have femoral and tibial component malpositioning during mechanically aligned total knee arthroplasty (TKA) and lower postoperative satisfaction. METHODS: This study included 146 knees in 117 Asian patients undergoing TKA for medial osteoarthritis. Preoperative bony morphological factors such as the angle between the femoral mechanical and anatomical axes (MA-AA angle), angle between the anatomical axes of the proximal and distal femur (lateral bowing femoral angle, LBFA), mechanical lateral distal femoral angle, medial proximal tibial angle, and % anatomical axis of the tibia were evaluated, as well as preoperative and 1-year postoperative 2011 Knee Society scores (KSSs). RESULTS: MA-AA angle and LBFA were significantly larger in knees with varus femoral component alignment versus neutral alignment. Preoperative MA-AA angle was underestimated in patients with larger MA-AA angle or LBFA, especially by inexperienced surgeons. Tibial morphological factors did not affect tibial component alignment. Changes in 2011 KSSs were similar among groups by lower limb alignment or femoral and tibial component alignment. CONCLUSION: Femoral bowing affects varus femoral component alignment by obscuring preoperative planning, but it had little impact on patient satisfaction when mechanical alignment is targeted during TKA.

"One millimetre equals one degree": a simple way to achieve in 92% of cases the desired correction after opening proximal tibial osteotomy for genu varum.

INTRODUCTION: When performing a high tibial osteotomy (HTO) for genu varum deformity, it is not always easy to obtain the correct amount of overcorrection. The aims of this study were to review the results of a simple and reproducible method of correction that we have called "1 mm equals 1°". We have applied this technique to the medial opening wedge osteotomy. Our hypothesis was that one degree of correction corresponded with one degree of opening. METHODS: 97 proximal medial opening wedge osteotomies were measured intraoperatively with a navigation system and at 3 months with long-leg X-rays. The hip-knee-ankle (HKA) angle preoperatively was on average 173.8 ± 2.3° (170°-177°). In most cases, an opening of 4° greater than the initial varus was performed using our formula that one degree varus was equal to 1 mm of opening. In other words, when the varus was 6°, an opening of 10 mm was performed. The void left by the opening wedge was filled with a calcium triphosphate wedge and the construct fixed and held with a locking plate. RESULTS: Aiming for a knee axis of 184 ± 2°, which corresponds to 2°-6° of overcorrection, we obtained the following results: HKA intraoperatively measured angle with navigation was on average 183.5 ± 0.9° (182°-184°) and HKA radiologically postoperatively angle was 182.5° ± 1.6° (179°-189°). We therefore achieved the desired overcorrection of 2°-6° in 92% of cases based on our postoperative radiographs and in 100% cases based on intraoperative measurements with computer navigation. CONCLUSION: The method of "1 mm equals 1°" is a simple, reliable, and reproducible method to achieve in 92% of cases the desired overcorrection (i.e., 184 ± 2°) with valgising proximal medial opening wedge osteotomy in genu varum.

Growth Modulation by Tension Band Plate in Achondroplasia With Varus Knee Deformity: Comparison of Gait Analysis Measurements.

BACKGROUND: Limited evidence exists concerning growth modulation by tension band plate (TBP) to correct varus deformity in patients with achondroplasia with limited growth due to FGFR3 gene mutation. We evaluated the efficacy of TBP in children with achondroplasia with genu varum and reported the static radiographic and dynamic motion data to determine parameters that impact the rate of deformity correction. METHODS: Patients with achondroplasia with genu varum who underwent TBP surgery for growth modulation were studied. Those with at least 1 year of follow-up with TBP were included. Radiographic parameters were measured. Growth velocity of femoral/tibial length was calculated separately. Patients were deemed successful or unsuccessful. Spearman correlation analysis and Student t test were used to describe statistical results. RESULTS: Twenty-two patients (41 limbs; 12 girls) fulfilled our criteria. Mean age at TBP surgery was 7.6±2.4 years. Thirty-six femoral TBP and 41 tibial TBP were in place for 24.5±9.7 months. Mean mechanical axis deviation, mechanical lateral distal femoral angle, and medial proximal tibial angle preoperatively were 30.1±7.6 mm, 97.2±6.4, and 80.3±4.3 degrees, and 11±15.6 mm, 87.4±5.9, and 84.7±5.3 degrees at last follow-up ( P <0.001). Fifteen limbs were successfully straightened; 4 limbs were in more varus than the initial deformity. Twenty-four limbs with TBP were still undergoing correction. In successful limbs, mean age at surgery was 6.5±1.7 years and duration of TBP was 29.9±7.8 months. In 4 unsuccessful limbs, mean age at surgery was 11.7±1.2 years. Analysis in the gait laboratory included physical examination with the measurement of knee varus and kinematic varus based on a posterior view static standing photograph. Photographic measurement of varus was higher than the radiographic measurement. CONCLUSIONS: Growth modulation by TBP surgery is a reliable and simple technique to correct genu varum in achondroplasia. An early age at TBP implementation (mean: 6.5 y) is crucial to successfully correct the varus knee deformity. Furthermore, we recommend early and regular surveillance of achondroplasia for progressive varus knee deformity. LEVEL OF EVIDENCE: Level IV-cohort study.

Double level osteotomy for genu varum: Is a return to sport possible?

INTRODUCTION: A double level osteotomy (DLO) may be indicated in patients with genu varum when the deformity involves both the tibia and femur. These patients, who are often young and active, have a high functional demand and hope for a rapid return to sport. The purpose of our study was to assess return to sport and functional outcomes following DLO for symptomatic genu varum. MATERIALS AND METHODS: A total of 40 patients (mean age 45.5±2 years) who underwent a DLO between 2018 and 2020, performed in 2 different hospitals, were reviewed after a minimum follow-up of 1-year. The mean initial varus was 11±2°. The type of sport and frequency of participation (UCLA activity score) as well as time to return to sport and level of activity recovered were defined as the primary endpoints. Functional scores were also assessed with the knee injury and osteoarthritis outcome score (KOOS). RESULTS: At the last follow-up, 87.5% (n=35) of patients reported that they had returned to sport. The mean time to return to sport was 6±1 months with a significant difference (p<0.001) between the pre- and postoperative UCLA activity scores. There was a strong correlation between the presence of a joint line obliquity >3° and decreased functional outcomes (p<0.0001). The overall KOOS score improved (p<0.001) by a mean of 38.6 points after the correction. The 8 lateral cortical fractures (Takeuchi type I and II) and the 2 medial cortical fractures (Nakayama type 1) that were found had no impact on functional outcomes (p>0.05). CONCLUSION: Our findings demonstrated that DLO provided rapid return to sport, thus making it possible to meet the functional demands and expectations of patients. LEVEL OF EVIDENCE: IV; Retrospective study.

Navigation makes more accurate femur resection compared to conventional total knee arthroplasty in lateral femoral bowing greater than 5º.

There are many disagreements about the merits of navigation in total knee arthroplasty (TKA). We compared and analyzed the difference in the accuracy of femoral resection according to the degree of lateral femoral bowing in 2 surgical methods (conventional and navigation-assisted TKA). A total of 238 (100 who underwent navigation TKA and 138 who underwent conventional TKA from 2016 to 2021) were included in this study. The surgeon first performed TKA as the main operator in 2016. Most of the TKAs were navigation-assisted between 2016 and 2018, and most of the TKAs were conventional between 2019 and 2021. For more accurate distal femoral cutting in patients with lateral femoral bowing, a preoperative scanogram was used to set up the insertion point of the IM rod in conventional TKA. Femoral lateral bowing was divided into 3 groups based on the angle. Group 1 was divided into groups with negative values, group 2 into mild bowing of 0° to 5°, and group 3 into groups with moderate bowing of ≥ 5°. The postoperative mechanical hip knee ankle angle and mechanical lateral distal femoral angle (mLDFA) were aimed to be 0° and 90°. The allowable ranges of these values were set as 0°â€…±â€…3° and 90°â€…±â€…3°, respectively. The distribution of outliers of the mLDFA in the 3 groups divided according to lateral femoral bowing in the navigation-assisted group was not statistically significant difference (P = .59). On the other hand, the distribution of outliers of mLDFA was statistically significant difference in the conventional method group (P = .01). The odds ratio of the outlier occurrence of mLDFA in the conventional method was 2.50, which was statistically significant (P = .03). Also, when the lateral femoral bowing value was moderate; i.e., ≥5°, the odds ratio was 4.20, which was statistically significant (P = .003). In the case of navigation-assisted TKA, the accuracy of femur resection was consistent regardless of the degree of lateral femoral bowing. However, in conventional TKA, the outlier of femur resection increased as lateral femoral bowing increased. Especially, for patients with lateral femoral bowing >5°, navigation-assisted TKA allows for more accurate femur resection compared to conventional TKA.

Coronal plane femoral bowing in Far East Asians: implications for the strategy of distal femoral resection in total knee arthroplasty.

BACKGROUND: The accuracy of distal femoral resection in intramedullary (IM) guided total knee arthroplasty (TKA) depends on femoral morphology and varies according to individual anatomy. This study aimed to characterise coronal plane femoral bowing in Far East Asians according to age, sex, and severity of varus deformity to identify optimal strategies for distal femoral resection in TKA. METHOD: Femoral anatomical parameters in 656 patients (M/F = 232:424) were assessed using standing long-leg anteroposterior radiography which was fulfilling strict standard. The femur was divided into three longitudinal segments to measure the segmental anatomical axial deviation from the mechanical axis and intersegmental bowing. Coronal plane femoral bowing pattern was categorised based on combined gross bowing and distal bowing. RESULTS: Mean hip-knee-ankle angle; neck-shaft angle; proximal, middle, and distal segmental axial differences; mechanical lateral distal femoral angle; and femur length were 6.7 ± 6.8°, 125.0 ± 5.5°, 5.9 ± 1.7°, 6.1 ± 1.1°, 5.3 ± 1.6°, 88.4 ± 2.6°, and 432.3 ± 23.9 mm in male and 8.4 ± 5.5°, 126.4 ± 5.6°, 5.4 ± 1.5°, 6.6 ± 0.9°, 5.6 ± 1.6°, 89.3 ± 2.6°, and 410.6 ± 23.3 mm in female, respectively. Mean proximal, distal, and gross femoral bowing was 0.3 ± 1.8°, - 0.8 ± 1.8°, and - 0.5 ± 2.9° in male and 1.2 ± 1.6°, - 1.0 ± 1.6°, and 0.2 ± 2.7° in female, respectively. CONCLUSIONS: Grossly straight femur with a straight distal part was the most common femoral bowing pattern in Far East Asians. Distal bowing was proved to be a key factor to choose method for distal femoral resection in TKA. Using IM-guide to achieve accurate distal femoral resection in the femora with distal segmental axial deviation between 4-8° and distal bowing less than ± 1° is considered feasible.

Comparison of femoral sagittal axis between navigated total knee arthroplasty and conventional total knee arthroplasty in patients with knee osteoarthritis.

To compare femoral sagittal axis between navigated total knee arthroplasty (TKA) and conventional TKA. A total of 136 cases were assigned to group 1 (navigated TKA) and 77 cases were assigned to group 2 (conventional TKA). Specifically, this study targeted patients with degenerative osteoarthritis. Only patients with primary TKA were analyzed. Hip knee ankle angle and lateral femoral bowing were measured using preoperative scanogram. Anterior femoral bowing was measured using preoperative femoral lateral X rays. The presence of anterior femoral notching and the insertion angle of the femoral implant with respect to the anatomical sagittal plane of the distal femur were checked using postoperative lateral knee X rays. Student t-test was used to compare the difference in the position of the sagittal plane of the femoral implant between the navigated TKA group and the conventional TKA group. When comparing the 2 groups, the sagittal axis of the femoral implant was more extended than the anatomical sagittal plane axis of the distal femur in group 1 than in group 2 (P = .01). There was a significant negative correlation between the value of anterior femoral bowing and the degree of flexion to the sagittal plane of the femoral implant in group 1 (correlation coefficient: -0.40, P = .01). The occurrence of anterior femoral notching was significantly higher in group 1 than in group 2. During navigated TKA, imageless navigation does not consider the anatomical variation of the femoral shaft. Therefore, surgeons should take into consideration that when performing navigated TKA, a femoral implant could be inserted more extended for the anatomical sagittal axis of the distal femur than for the conventional TKA. Also, surgeon should know that the degree of extension insertion of the femoral implant increases as femoral anterior bowing increases.

Bilateral genu varum deformity correction in an adult by medial opening-wedge high tibial osteotomy without internal fixation.

A young adult man in 20s presented with bow leg deformity of both the knees, since childhood and bilateral knee pain for the last 4 years. Plain radiographs of both the knees confirmed bilateral genu varum deformity, more on the right side (16.2°) as compared with left (12.3°). He was managed surgically by a single-stage bilateral medial opening wedge high tibial osteotomy, using a synthetic bone substitute of a tri calcium phosphate. After the healing of osteotomies at 3 months, the patient was pain free and walked comfortably with normal lower limb alignment.

Varus morphology and its surgical implication in osteoarthritic knee and total knee arthroplasty.

BACKGROUND: Knee varus alignment represents a notorious cause of knee osteoarthritis. It can be caused by tibial deformity, combined tibial-femoral deformity and/or ligament imbalance. Understanding malalignment is crucial in total knee arthroplasty to restore frontal plane neutral mechanical axis. The aim of this study was to determine which factor contributes the most to varus osteoarthritic knee and its related surgical implications in performing a total knee arthroplasty. METHODS: We retrospectively evaluated 140 patients operated for total knee arthroplasty due to a varus knee. Full-leg hip to ankle preoperative X-rays were taken. Radiological parameters recorded were: mechanical axis deviation, hip-knee-ankle, anatomical-mechanical angle, medial neck shaft angle, mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), lateral proximal femoral angle, lateral distal tibial angle (LDTA), femoral bowing, and length of tibia and femur. We also determined ideals tibial and femoral cuts in mm according to mechanical alignment technique. A R2 was calculated based on the linear regression between the predicted values and the observed data. RESULTS: The greatest contributor to arthritic varus (R = 0.444) was MPTA. Minor contributors were mLDFA (R = 0.076), JLCA (R = 0.1554), LDTA (R = 0.065), and femoral bowing (R = 0.049). We recorded an average of 7.6 mm in lateral tibial cut thickness to restore neutral alignment. CONCLUSIONS: The radiological major contributor to osteoarthritic varus knee alignment is related to proximal tibia deformity. As a surgical consequence, during performing total knee arthroplasty, the majority of the correction should therefore be made on tibial cut.

Sagittal femoral bowing contributes to distal femoral valgus angle deviation in malrotated preoperative radiographs.

BACKGROUND: The coronal whole-leg radiograph is generally used for preoperative planning in total knee arthroplasty. The distal femoral valgus angle (DFVA) is measured for distal femoral bone resection using an intramedullary guide rod. The effect of coronal and sagittal femoral shaft bowing on DFVA measurement in the presence of malrotation or knee flexion contracture has not been well reported. The objectives of this study were: (1) to investigate the effects of whole-leg malrotation and knee flexion contracture on the DFVA in detail, (2) to determine the additional effect of coronal or sagittal femoral shaft bowing. METHODS: We studied 100 consecutive varus and 100 valgus knees that underwent total or unicompartmental knee arthroplasty. Preoperative CT scans were used to create digitally reconstructed radiography (DRR) images in neutral rotation (NR, parallel to the surgical epicondylar axis), and at 5° and 10° external rotation (ER) and internal rotation (IR). The images were also reconstructed at 10° femoral flexion. The DFVA was evaluated in each DRR image, and the angular variation due to lower limb malposition was investigated. RESULTS: The DFVA increased as the DRR image shifted from IR to ER, and all angles increased further from extension to 10° flexion. The DFVA variation in each position was 1.3° on average. A larger variation than 2° was seen in 12% of all. Multivariate regression analysis showed that sagittal femoral shaft bowing was independently associated with a large variation of DFVA. Receiver operating characteristic analysis showed that more than 12° of sagittal bowing caused the variation. CONCLUSION: If femoral sagittal bowing is more than 12°, close attention should be paid to the lower limb position when taking whole-leg radiographs. Preoperative planning with whole-leg CT data should be considered.

The accuracy of an extramedullary femoral cutting system in total knee arthroplasty in patients with severe coronal femoral bowing: a radiographic study.

BACKGROUND: Intramedullary (IM) femoral alignment instrument is imprecise for the coronal alignment in total knee arthroplasty (TKA) in patients with severe lateral bowing of the femur, while the extramedullary (EM) alignment system does not depend on the structure of the femoral medullary cavity. The aim of this retrospective study was to compare the accuracy of postoperative limb alignment with the two femoral alignment techniques for patients with severe coronal femoral bowing. METHODS: From January 2017 to December 2019, patients with end-stage knee osteoarthritis and coronal femoral bowing angle (cFBA) ≥ 5° who underwent total knee arthroplasty TKA at our institution were enrolled in the study. The postoperative hip-knee-ankle (HKA) alignment, femoral and tibial component alignment between the IM group and the EM group were compared on 5° ≤ cFBA < 10° and cFBA ≥ 10°. RESULTS: In patients with 5° ≤ cFBA < 10°, no significant differences were observed in the EM group and IM group, including preoperative and postoperative parameters. However, when analyzing the patients with cFBA ≥ 10°, we found a significant difference in postoperative HKA (4.51° in the IM group vs. 2.23°in the EM group, p < 0.001), femoral component alignment angle (86.84° in the IM group vs. 88.46° in the EM group, p = 0.001) and tibial component alignment angle (88.69° in the IM group vs. 89.81° in the EM group, p = 0.003) between the two groups. Compared to the EM group, the IM group presents a higher rate of outliers for the postoperative HKA and femoral components. CONCLUSIONS: The study showed that severe lateral bowing of the femur has an important influence on the postoperative alignment with the IM femoral cutting system. In this case, the application of EM cutting system in TKA will perform accurate distal femoral resection and optimize the alignment of lower limb and the femoral component.

Factors Affecting Rebound Phenomenon After Temporary Hemiepiphysiodesis and Implant Removal for Idiopathic Genu Valgum in Adolescent Patients.

BACKGROUND: The aim of this study was to investigate factors determining postoperative courses, especially focusing on the rebound phenomenon, in adolescent patients with idiopathic genu valgum who underwent temporary hemiepiphysiodesis and implant removal. METHODS: We identified and reviewed patients with idiopathic genu valgum treated with temporary hemiepiphysiodesis [using tension-band plates (plate group, PG) or transphyseal screws (screw group, SG)] and followed-up to skeletal maturity. RESULTS: In our cohort [68 patients and their 68 limbs (randomly selected in bilateral cases)], the mean hip-knee-ankle alignment was -5.4±1.8 degrees at the time of temporary hemiepiphysiodesis (negative means valgus), 2.6±2.1 degrees at the time of implant removal, and 0.7±2.6 degrees at the last follow-up, respectively. Regarding the implants, the correction speed was not significantly different (P=0.192-0.315) between the PG (total 1.29±0.37 degrees/mo, 0.71±0.23 degrees/mo at distal femur, 0.59±0.16 degrees/mo at proximal tibia, n=19) and the SG (total 1.22±0.49 degrees/mo, 0.65±0.25 degrees/mo at distal femur, 0.57±0.23 degrees/mo at proximal tibia, n=49). The magnitude of rebound phenomenon in the PG (4.1±1.9 degrees) was greater (P<0.001) than that in the SG (1.1±3.1 degrees). The use of plates and faster correction speed, rather than more severe preoperative deformity or greater correction angle, were positively associated with the rebound phenomenon in regression analyses. Among the 68 knees, 1 showed valgus alignment ≥5 degrees and 5 showed varus alignment ≥5 degrees at the last follow-up. All the 6 cases were observed in the SG. Surgical wound dehiscence was observed in 1 patient in the PG. CONCLUSIONS: The use of plates and faster correction speed were positively associated with the rebound phenomenon. Careful attention will be needed with the corresponding conditions for optimal results. Progressive genu varum after transphyseal screw removal, which was observed in this study, should be explored in future research. LEVEL OF EVIDENCE: Level III-retrospective comparative series.

A Flexible Intramedullary Guide Can Reduce the Anteroposterior Oversizing of Femoral Components Used in Total Knee Arthroplasty in Patients with Osteoarthritis and Severe Distal Femoral Sagittal Bowing.

Traditionally, a rigid intramedullary rod has been used as the reference guide for femoral cutting in total knee arthroplasty (TKA). However, correct positioning of this rigid rod is difficult, especially in the knees with severe distal femoral sagittal bowing. A flexible intramedullary rod has been developed to address this problem. This study was performed to compare the sagittal alignment and clinical outcomes of TKAs performed with flexible and rigid femoral intramedullary guides. Thirty-eight knees that underwent primary TKAs with flexible intramedullary rods as femoral cutting guides were matched according to patient height and sex with 38 knees that underwent TKAs using conventional rigid rods. Clinical outcomes, including the range of motion and functional scores, and radiological variables, including the distal femoral bowing angle (DFBA), femoral component flexion angle (FFA), and mediolateral overhang and anteroposterior (AP) oversizing of femoral components, were evaluated. Clinical and radiological outcomes did not differ significantly between the flexible rod and conventional rigid rod groups. A subgroup analysis of knees with severe distal femoral sagittal bowing (DFBA >4 degrees) showed that the FFA was significantly larger in the flexible rod group than in the rigid rod group, with an average difference of 3 degrees (5.2 ± 2.4 vs. 2.2 ± 1.6 degrees, respectively, p = 0.022). In addition, the incidence of AP oversizing of femoral components was lower in the flexible rod group than in the rigid rod group (11.1 vs. 60.0%, respectively, p = 0.027). Relative to TKA with a rigid rod, TKA performed with a flexible femoral intramedullary guide resulted in more flexed sagittal alignment of femoral components in patients with severe distal femoral sagittal bowing. This greater flexion of the femoral component resulted in less AP oversizing. However, the use of a flexible rod had no impact on short-term clinical outcomes.

Percutaneous high tibial closed-wedge corticotomy and casting for treating genu varum in adolescents.

PURPOSE: Diverse surgical modalities have been designated for the treatment of genu varum deformity. However, other studies have not constantly confirmed which technique to be better than the other. The use of hardware, bone graft or bone substitute have their own risks. In this study, simple technique of percutaneous high tibial closed-wedge corticotomy and casting for treating genu varum in average body-built adolescents without hardware fixation was reported. METHODS: An overall 22 knees of 16 average-weight adolescents having genu varum with a mean age of 14.8 years (range, 12-18 years) underwent percutaneous high tibial closed-wedge corticotomy and casting. The study was conducted between May 2017 and January 2020. The typical follow-up duration was ten months (range, 8-22 months). Clinical and radiological evaluation for all patients was implemented. RESULTS: Mean postoperative Rasmussen clinical score was 27 (range, 24-30), with 16 excellent and six good results. The tibiofemoral angle improved from a mean of 18.2 degree varus (range, 14-25 degree varus) preoperatively to 1.3 degree valgus (range, 0-8 degree valgus) postoperatively, indicating a significant improvement (P < 0.05). Bone union was achieved at a mean of ten weeks (range, 8-14 weeks). None of the patients sustained nonunion, delayed union, infection, or knee stiffness. CONCLUSIONS: Percutaneous high tibial closed-wedge corticotomy and casting is a minimally invasive procedure for treating genu varum in adolescents. Good results are able to be attained with proper patient selection and meticulous surgical technique.