Coronal Alignment Research Articles

Hindfoot Alignment in Flexible Cavovarus Deformity Under Orthostatic and Coleman Block Test Positions: A Weightbearing Computed Tomography Study.

Flexible cavovarus deformity is prevalent and the Coleman block test is frequently used to assess the first ray plantarflexion malpositioning in the overall deformity as well as the flexibility of the hindfoot. The objective was to assess and compare the weightbearing computed tomography (WBCT) 3-dimensional (3D) changes in clinical and bone alignment in flexible cavovarus deformity patients when performing the Coleman block test when compared to normal standing position and to controls. Twenty patients (40 feet) with flexible cavovarus deformity and 20 volunteer controls (40 feet) with normal foot alignment underwent WBCT imaging of the foot and ankle. Cavovarus patients were assessed in normal orthostatic and Coleman block test positions. Foot and ankle offset (FAO), hindfoot alignment angle (HAA), talocalcaneal angle (TCA), subtalar vertical angle (SVA) and talonavicular coverage angle (TNCA) and a CT-simulated soft tissue envelope image, WBCT clinical hindfoot alignment angle (WBCT-CHAA), were evaluated by 2 readers. Measurements were compared between cavovarus nonstressed and stressed positions and to controls. P values of .05 or less were considered significant. The intra- and interobserver intraclass correlation coefficient were good or excellent for all WBCT measurements. Cavovarus patients demonstrated significant correction of WBCT-CHAA (9.7 ± 0.4 degrees), FAO (2.6 ± 0.4%), and TNCA (8.8 ± 1.8 degrees) when performing the Coleman block test (all P values <.0001). However, WBCT-CHAA and FAO measurements were still residually deformed and significantly different from controls (P values of .001 and <.0001, respectively). TNCA values corrected to values similar to healthy controls (P = .29). No differences were observed in cavovarus patients during Coleman block test for the coronal measures: HAA, TCA, and SVA measurements. In this study, we observed improvement in the overall 3D WBCT alignment (FAO), axial plane adduction deformity (TNCA), as well as CT simulated clinical hindfoot alignment (WBCT-CHAA) in flexible cavovarus deformity patients when performing a Coleman block test. However, we did not find improvement in measures of coronal alignment of the hindfoot, indicating continued varus positioning of the hindfoot in these patients.

THE USE OF A TIBIA REDUCTION DEVICE IN THE TREATMENT OF FRACTURES UNDERGOING TIBIAL NAILING AT A DISTRICT GENERAL HOSPITAL: A PARALLEL CASE SERIES

Malalignment is a common complication following tibial surgery, occurring in 10% of fractures. This is associated with prolonged healing time and non-union. It occurs due to inability to maintain a satisfactory reduction. A reduction device, such as the Staffordshire Orthopaedic Reduction Machine (STORM), permits the surgeon to manipulate the fracture and hold it reduced.A retrospective parallel case series was undertaken of all patients undergoing tibial nails over a six-year period from 2014 to 2021. Patient demographics were obtained from medical records. Operative times obtained from the theatre IT system and included the time patient entered theatre and surgical start and finish times for each case.Anteroposterior and lateral long leg post-operative radiographs were reviewed. Angulation was measured in both coronal and sagittal planes, by two separate orthopaedic surgeons. A reduction was classified to be ‘mal-aligned’ if the angle measured was greater than 5 degrees. One tailed unpaired t-test was used to compare alignment in each plane. Bony union was assessed on subsequent radiographs and was determined according to the Radiographic Union Score for Tibial Fractures31 patients underwent tibial nail during the time period. 8 patients were lost to follow up and were excluded. Of the remaining 23 patients, the STORM device was utilised in 11.The overall mean alignment was acceptable across all groups at 2.17° in the coronal plane and 2.56° in the saggital plane. Analysing each group individually demonstrated an improved alignment when STORM was utilised: 1.7° (1°–3°) vs 2.54° (0°–5°) for the coronal plane and 1.6° (0°–3°) vs 3.31° (0°–9°) in the saggital plane. This difference was significant in saggital alignment (p=0.03) and showed a positive trend in coronal alignment, although was not significant (p=0.08)The time in theatre was shorter in the control group with a mean of 113 minutes (65 to 219) in comparison to STORM with a mean of 140 minutes (105 to 180), an increased theatre time of 27 minutes (p=0.04).This study demonstrates that STORM can be used in the surgical treatment of tibial fractures resulting in improved fracture alignment with a modest increase in theatre time.

Radiological Assessment of Coronal Plane Alignment of the Knee Phenotypes in the Romanian Population.

Background: The Coronal Plane Alignment of the Knee (CPAK) classification system has been developed as a comprehensive framework delineating nine coronal plane phenotypes, based on arithmetic hip-knee angle (aHKA) and joint line obliquity (JLO). Our study aimed to assess the prevalence of knee phenotypes in the Romanian population using the CPAK classification, encompassing both osteoarthritic and healthy cohorts. Methods: We conducted an observational cross-sectional study, analyzing data from 500 knees with osteoarthritis and 500 healthy knees that met the inclusion criteria. Demographic data were collected, and radiological parameters including lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), aHKA, and JLO were measured. Knee phenotypes were categorized using the CPAK classification. Results: In the osteoarthritic cohort, the most prevalent CPAK phenotype was type I (42.4%), characterized by varus alignment and an apex distal joint. Conversely, in the healthy population, CPAK type II, indicating neutral alignment and an apex distal joint, was the most prevalent phenotype (39.0%). CPAK types VII, VIII, and IX were rare. Conclusions: Our findings demonstrate similarities in knee phenotypes compared to other populations, with some minor differences and particularities. The CPAK classification proves to be a valuable tool in assessing knee tyalignment.

Tibial insert design significantly alters knee kinematics using a single cruciate-retaining total knee implant.

Patient dissatisfaction is not uncommon following primary total knee arthroplasty. One proposed method to alleviate this is by improving knee kinematics. Therefore, we aimed to answer the following research question: are there significant differences in knee kinematics based on the design of the tibial insert (cruciate-retaining (CR), ultra-congruent (UC), or medial congruent (MC))? Overall, 15 cadaveric knee joints were examined with a CR implant with three different tibial inserts (CR, UC, and MC) using an established knee joint simulator. The effects on coronal alignment, medial and lateral femoral roll back, femorotibial rotation, bony rotations (femur, tibia, and patella), and patellofemoral length ratios were determined. No statistically significant differences were found regarding coronal alignment (p = 0.087 to p = 0.832). The medial congruent insert demonstrated restricted femoral roll back (mean medial 37.57 mm; lateral 36.34 mm), while the CR insert demonstrated the greatest roll back (medial 42.21 mm; lateral 37.88 mm; p < 0.001, respectively). Femorotibial rotation was greatest with the CR insert with 2.45° (SD 4.75°), then the UC insert with 1.31° (SD 4.15°; p < 0.001), and lowest with the medial congruent insert with 0.8° (SD 4.24°; p < 0.001). The most pronounced patella shift, but lowest patellar rotation, was noted with the CR insert. The MC insert demonstrated the highest level of constraint of these inserts. Femoral roll back, femorotibial rotation, and single bony rotations were lowest with the MC insert. The patella showed less shifting with the MC insert, but there was significantly increased rotation. While the medial congruent insert was found to have highest constraint, it remains uncertain if this implant recreates native knee kinematics or if this will result in improved patient satisfaction.

Mechanically aligned total knee arthroplasty does not yield uniform outcomes across all coronal plane alignment of the knee (CPAK) phenotypes.

Patient dissatisfaction rates following total knee arthroplasty (TKA) reported in the literature reach 20%. The optimal coronal alignment is still under debate. The aim of this retrospective study was to compare clinical outcomes in different coronal plane alignment of the knee (CPAK) phenotypes undergoing mechanically aligned (MA) TKA. The hypothesis was that knees with preoperative varus arithmetic hip-knee-ankle angle (aHKA) would achieve inferior clinical outcomes after surgery compared to other aHKA categories. Additionally, another objective was to assess CPAK phenotypes distribution in the study population. A retrospective selection was made of 180 patients who underwent MA TKA from April 2021 to December 2022, with a 1-year follow-up. Coronal knee alignment was classified according to the CPAK classification. Clinical outcome evaluations were measured using the Knee Society Score (KSS), Oxford Knee Score (OKS), Short Form Survey 12and Forgotten Joint Score (FJS). Differences in clinical outcomes were considered statistically significant with a p value <0 .05. Patients with varus aHKA achieved significantly inferior outcomes at final follow-up compared to other aHKA categories in KSS pt. 1 (79.7 ± 17.2 vs. 85.6 ± 14.7; p = 0.028), OKS (39.2 ± 9.2 vs. 42.2 ± 7.2; p = 0.019) and FJS (75.4 ± 31.0 vs. 87.4 ± 22.9; p =0 .003). The most common aHKA category was the varus category (39%). The most common CPAK phenotypes were apex distal Types I (23.9%), II (22.8%)and III (13.3%). MA TKA does not yield uniform outcomes across all CPAK phenotypes. Varus aHKA category shows significantly inferior results at final follow-up. The most prevalent CPAK categories are varus aHKA and apex distal JLO, with phenotypes I, IIand III being the most common. However, their gender distribution varies significantly. Level IV.

Femorotibial angle scan-rescan reproducibility: A high-precision calculation on a large cohort.

Femorotibial angle (FTA) is a convenient measure of coronal knee alignment that can be extracted from a short knee radiograph, avoiding the additional radiation exposure and specialist equipment required for full-leg radiographs. While intra- and inter-reader reproducibility from the same image has been reported, the full scan-rescan reproducibility across images, as calculated in this study, has not. In this study, 4589 FTA measurement pairs from 2586 subjects acquired a year apart were used to estimate FTA scan-rescan reproducibility using data from the Osteoarthritis Initiative. Subjects with radiographic progression of osteoarthritis or other conditions that may cause a change in coronal knee alignment were excluded. Measurement pairs were analysed using paired-samples tests to detect differences and compared to symptomatic changes in Western Ontario and McMaster Universities Arthritis Index scores for joint pain, stiffnessand physical function to detect correlations. The 95% limit of agreement and the paired-samplescorrelation were calculated with high precision to be [-1.76°, +1.78°] and 0.938, considerably worse than the corresponding figures for intra- and inter-reader reproducibility, without relation to symptomatic or radiographic changes in knee condition. This error will weakly attenuate and values from their true values in correlative studies involving FTA. The realistic maximum value for is 87%and for Pearson's is 93%. The scan-rescan reproducibility in FTAis almost double the intra- and inter-reader reliability from a single scan. At almost ±2° accuracy, FTA is inappropriate for surgical use, but it is sufficiently reproducible to produce good correlations in studies predicting disease incidence and progression. Level II, retrospective study.

Evaluation of the effect of vascularized fibula graft harvesting on coronal plane alignment and functional outcomes of the lower limb

Recent studies on fibular osteotomy for varus gonarthrosis and possible subsequent biomechanical changes have attracted increasing attention to the topic. Existing studies have focused mainly on proximal fibular osteotomy with short follow-up periods. The aim of this study was to investigate changes in the alignment of the coronal plane of the ankle and knee joints in patients who underwent vascularized fibula graft harvest (VFGH). The evaluation was based on functional outcomes and radiological measurements.In the comparison between the VFGH side and the contralateral side, no significant differences in the knee inclination (KI) or talar inclination (TI) angle, knee medial clear space (K-MCS) or ankle medial clear space (A-MCS) distance were noted. However, a significant difference in the hip knee (HKA) angle was observed between the operated and nonoperated sides (0.3° ± 1.8° and 1.5° ± 1.9°, respectively [p = 0.019]). Statistically significant differences in both the knee society score (KSS) and the AOFAS scores were found between the ipsilateral donor limb and the contralateral healthy limb. Although the contralateral healthy side had better clinical scores than the VFGH side, the outcomes of the VFGH side were still satisfactory or excellent.

Increased prevalence of valgus constitutional alignment subtypes in a South African arthritic population group using the coronal plane alignment of the knee (CPAK) classification

BackgroundKnee alignment philosophies and patient specific models to improve patient reported outcomes are gaining increasing attention. The coronal plane alignment of the knee (CPAK) classification describes nine knee phenotypes and then proposes surgical alignment strategies to achieve constitutional alignment. The CPAK classification has been validated in Australian, European, Asian and North American population groups. To date no African data has been analyzed using CPAK. MethodsA total of 344 arthritic patients (608 knees) with appropriate long leg radiographs were classified based on the CPAK type. Measurements included mechanical hip-knee-angle(mHKA), medial proximal tibial angle (mMPTA) and lateral distal femoral angle (mLDFA) and the derived calculations of joint line obliquity (JLO) and arithmetic hip-knee-angle (aHKA). ResultsThe sample population was 77.9% (n = 268) female with a mean age of 68.4 ± 9.2 years. The most common CPAK types in order were type 3 (n = 174; 28.6%), type 2 (n = 155; 25.5%), type 1 (n = 94; 15.5%) and type 6 (n = 80; 13.2%). The most common limb alignment types were valgus (CPAK types 3,6,9; 41.8%). ConclusionThis study, which investigated arthritic patients from a single institution in South Africa, shows a divergence of CPAK phenotypic knee patterns relative to other international studies, with much higher proportions of valgus phenotypes (3 and 6). This regional difference should be further investigated in other South African and African population samples and used to adapt the surgical strategies employed by local surgeons.

Nonoperative Treatment of Humeral Shaft Fractures With Immediate Functional Bracing Versus Coaptation Splinting and Delayed Functional Bracing: A Retrospective Study.

To compare radiographic and clinical outcomes in nonoperative management of humeral shaft fractures treated initially with coaptation splinting (CS) followed by delayed functional bracing (FB) versus treatment with immediate FB. Retrospective cohort study. Academic Level 1 Trauma Center. Patients with closed humeral shaft fractures managed nonoperatively with initial CS followed by delayed FB or with immediate FB from 2016 to 2022. Patients younger than 18 years and/or with less than 3 months of follow-up were excluded. The primary outcome was coronal and sagittal radiographic alignment assessed at the final follow-up. Secondary outcomes included rate of failure of nonoperative management (defined as surgical conversion and/or fracture nonunion), fracture union, and skin complications secondary to splint/brace wear. Ninety-seven patients were managed nonoperatively with delayed FB (n = 58) or immediate FB (n = 39). Overall, the mean age was 49.9 years (range 18-94 years), and 64 (66%) patients were female. The immediate FB group had less smokers ( P = 0.003) and lower incidence of radial nerve palsy ( P = 0.025), with more proximal third humeral shaft fractures ( P = 0.001). There were no other significant differences in demographic or clinical characteristics ( P > 0.05). There were no significant differences in coronal ( P = 0.144) or sagittal ( P = 0.763) radiographic alignment between the groups. In total, 33 (34.0%) humeral shaft fractures failed nonoperative management, with 11 (28.2%) in the immediate FB group and 22 (37.9%) in the delayed FB group ( P = 0.322). There were no significant differences in fracture union ( P = 0.074) or skin complications ( P = 0.259) between the groups. This study demonstrated that nonoperative treatment of humeral shaft fractures with immediate functional bracing did not result in significantly different radiographic or clinical outcomes compared to treatment with CS followed by delayed functional bracing. Future prospective studies assessing patient-reported outcomes will further guide clinical decision making. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Large angular correction of arithmetic coronal alignment is associated with residual lateral laxity after total knee arthroplasty in varus knees for Japanese patients.

One of the most common types of coronal plane alignment of the knee (CPAK) is type I, which is characterised by varus alignment and apex distal joint line obliquity. The purpose of this study was to evaluate the association of changes in arithmetic hip-knee-ankle angle (aHKA) with both postoperative joint laxity and patient-reported outcome measures (PROMs) in patients with CPAK type I following mechanical alignment (MA) total knee arthroplasty (TKA). Of 111 consecutive knees in 92 patients with osteoarthritis who underwent primary TKA, 80 knees (72.0%) with CPAK type I phenotype preoperatively were evaluated. All TKAs were performed to achieve neutral MA by a medial stabilising gap balancing technique. Pre- to postoperative change in aHKA was defined as ΔaHKA. The 80 CPAK type I knees were divided into a larger ΔaHKA group (>7°) and a smaller ΔaHKA group (≤7°). PROMs, including the Knee Society Score and Forgotten Joint Score-12, were assessed before and 2 years after surgery. Pre- and postoperative joint laxity was assessed using a Telos arthrometer. Twenty-two knees showed a larger ΔaHKA, and postoperative lateral joint laxity in varus stress was significantly greater in these patients than in those with a smaller ΔaHKA (6.8° vs. 4.5°, p = 0.006). There were no significant differences between the groups in PROMs (p = n.s.). Postoperative lateral laxity was associated with larger aHKA changes than smaller aHKA changes in CPAK type I knees after TKA. However, no statistically significant differences in PROMs were found according to the amount of change in aHKA. Level III.

Poster 249: Distal Femoral Coronal Realignment Osteotomies Alter CT-Measured Tibial Tuberosity to Trochlear Groove (TT-TG) Distance in Addition to Mechanical Axis Deviation – A Cadaveric Study

Objectives: Patellar tracking has been shown to be affected by limb alignment. Many patients with underlying valgus deformity with patellar instability have elevated tibial tuberosity–trochlear groove (TT-TG) measurements. Correction of limb alignment improves Q-angle, however, its effect on TT-TG as measured by computed tomography (CT) has yet to be demonstrated. We hypothesize that changing the limb alignment as measured by mechanical axis deviation (MAD) through a distal femoral osteotomy (DFO) would also cause a change in TT-TG distance as measured by CT. Methods: Lateral distal femoral osteotomies were performed on 5 cadaveric specimens (10 limbs) and fixed with an external fixator. The native MAD and baseline TT-TG were measured using a CT scanogram. Subsequent scans were then performed altering the MAD using calibrated radiolucent wedges in 5 mm increments (0-25 mm) on a single side, using the contralateral limb as the control. Repeat measurements of MAD and TT-TG were obtained, and once completed, original alignment was restored, and the contralateral limb was taken through the same protocol with the opposite limb serving as the control. Measurements were performed by two independent observers and averages obtained. Linear regression models were created, and statistical analysis of variance was performed. Results: A CT-scanogram that measured TT-TG distances were significantly altered by changes in limb alignment. According to our linear regression model, each 1° of MAD alteration resulted in TT-TG change of approximately 0.4 mm. With every 5° change in limb alignment, the TT-TG changed by approximately 2 mm (Figure 1). Altering MAD from 6° valgus to 7° varus decreased the TT-TG mean from 14.3 mm to 7.7 mm, p &lt; 0.05. Conclusions: Changes in coronal limb alignment through a distal femoral corrective osteotomy produce significant changes in TT-TG in addition to correcting MAD in a cadaveric model. These findings should be considered when determining appropriate corrective procedures for patients with valgus alignment and patellar instability. [Figure: see text]

Glass Tracing Alignment Method: A Novel, Low-Cost Coronal and Sagittal Alignment Transfer Method for Lower-Limb Prostheses

Glass Tracing Alignment Method: A Novel, Low-Cost Coronal and Sagittal Alignment Transfer Method for Lower-Limb Prostheses

Computer-assisted revision total knee arthroplasty does not improve postoperative knee prosthesis alignment compared to the conventional technique.

Computer-assisted surgery (CAS) during primary total knee arthroplasty (TKA) prosthesis alignment. However, literature on its use during revision TKA (rTKA) is scarce. Moreover, the effect of CAS during rTKA on rotational alignment of the prosthesis has not been described yet. The purpose of this study was to assess the effect of CAS during rTKA, focusing on the number of outliers and coronal, sagittaland rotational prosthetic alignment compared to conventional rTKA. A prospective cohort study comparing CAS-rTKA with a historical control group (CON-rTKA). The CAS-rTKA group (54 patients/62 knees) underwent rTKA using imageless CAS between 2012 and 2017. The CON-rTKA group (13 patients/23 knees) was operated using the conventional technique between 2002 and 2012. Postoperative alignment was measured using the EOS-2D/3D system (coronal and sagittal planes) and computed tomographyscan (rotation). No significant differences between the CAS-rTKA and CON-rTKA groups were found for coronal and sagittal alignment regarding the mechanical angle of the leg (p = 0.08), mechanical lateral distal femoral angle (p = 0.87), mechanical medial proximal tibial angle (p = 0.40), anatomical proximal posterior tibial angle (p = 0.43) nor femoral (p = 0.80) and tibial rotation (p = 0.15). For the proportions of coronal, sagittaland rotational outliers, no significant differences were found either. This study showed no evidence that use of CAS during rTKA leads to improved coronal, sagittalor rotational alignment of knee prosthesesor a difference of outliers between the groups. Level III, therapeutic.

Double-level osteotomy for varus knees using patient-specific cutting guides allow more accurate correction but similar clinical outcomes as compared to conventional techniques

PurposePatient-specific cutting guides are increasingly used in the field of osteotomies around the knee and can improve the accuracy of planned correction and more specifically in the case of double-level osteotomy (DLO). The purpose of this study was to analyse the accuracy of postoperative coronal alignment after DLO using patient-specific cutting guides techniques (PSI) compared to conventional techniques.The secondary objective was to compare the functional results between the two groups at short-term follow-up. HypothesisThe accuracy of global correction (HKA angle) is better with patient-specific cutting guides compared to conventional techniques for double-level osteotomy MethodsThis multicentric comparative retrospective study included 53 patients (mean age: 53.8 ± 5.2 years, male/female: 44/9) who underwent a DLO for knee varus malalignment. The coronal correction accuracy (as expressed by the difference between postoperative angular values and preoperative targeted correction) was compared between techniques using patient-specific cutting guides (PSI group, n = 27) or conventional techniques (n = 26) for the medial proximal tibial angle (MPTA) and the lateral distal femoral angle (LDFA). Postoperatively, the global alignment expressed by the hip-knee-ankle angle and the joint line obliquity were compared between groups. The postoperative functional results for KOOS and UCLA activity scale score were also compared at a mean follow-up of 1.7 years (1.0–3.1 years). ResultsNo difference was observed for the postoperative global alignment between the PSI and the conventional groups (Δ = 0.6 °, p = 0.11) neither for the postoperative posterior proximal tibial angle (Δ = 1.6°, p = 0,99) or the joint line obliquity (Δ = 0.3°, p = 0,17). In the coronal plane, the postoperative MPTA was lower in the PSI group (Δ = 2.3°, p < 0.001) as well as the postoperative LDFA (Δ = 0.9°, p = 0.01).Concerning correction accuracy in the coronal plane, the results showed a significant higher accuracy of the planned correction in the PSI group compared to the conventional group for MPTA (2.2 ± 0.2 versus 0.8 ± 0.7, Δ = 1.5 °, p < 0.001) and LDFA (1.3 ± 1.0 versus 0.6 ± 0.9, Δ = 0.7°, p < 0.001).No improvement difference was observed between the conventional group and the PSI group respectively for the KOOS symptoms (p = 0.12), the KOOS Pain (p = 0,57), the KOOS activities of daily living (p = 0.61), the KOOS sport/rec (p = 0.65), or for the KOOS Quality of Life (p = 0.99) neither for the UCLA (p = 0.97). ConclusionsThis study suggests that the use of custom-made cutting guides improves the accuracy of planned correction in double-level osteotomy compared with conventional techniques, which may have implications particularly in centers not performing a large volume of osteotomies.This improved accuracy is not associated with any difference in joint line obliquity or functional results but these results need to be confirmed by a randomized prospective study. Level of evidence: III; Retrospective comparative study

Femorotibial angle on short knee radiographs fails to accurately predict the lower limb mechanical alignment. A systematic review and meta-analysis on different femorotibial angle definitions and short knee radiograph types.

Hip-knee-ankle angle (HKA) on Full Limb Radiographs (FLRs) is the gold standard for coronal knee alignment assessment. Despite the widespread utilization of the more convenient femorotibial angle (FTA) on either antero-posterior (AP) or postero-anterior (PA) short knee radiographs (SKRs), its definition and correlation with HKA remains controversial. This review is the first to systematically investigate FTA-HKA correlation and the effect of different FTA methods and SKRs. Systematic literature search (Pubmed, Scopus, Cochrane Library) followed PRISMA guidelines, to evaluate studies examining the FTA-HKA correlation. Meta-analyses compared the 3 most common FTA methods, knee center determination method and SKR types. 17 studies (2597 patients, 3234 knees) were included. The strongest correlation with HKA (r = 0.78) was found for FTA Method 1 (angle formed by lines drawn from the midpoint of tibial spines to points 10 cm above and below the joint line). No significant differences were observed when grouping the FTA methods by knee center assessment (Group I, r = 0.78; Group II, r = 0.77). AP SKRs showed a trend towards stronger FTA-HKA correlation compared to PA SKRs, in both Method 1 (r = 0.79 vs 0.75) and Method 3 (r = 0.80 vs 0.66). Irrespective of its definition or type of SKR used, FTA lacks reliable accuracy in predicting the HKA in most knees. FLRs should be used whenever precise estimation of the patient's alignment is necessary. Caution is warranted in interpreting studies investigating knee alignment or knee arthroplasty outcomes based on FTA.

Postoperative Medial Malleolar Fractures in Total Ankle Replacement Are Associated With Decreased Medial Malleolar Width and Varus Malalignment: A Case-Control Study.

There are limited data regarding risk factors associated with periprosthetic medial malleolar fractures in total ankle arthroplasty (TAA). This case-control study aimed to identify the risk factors and analyze the effect of prophylactic screw fixation in preventing a medial malleolar fracture after TAA. A case-control study was conducted on 149 patients who underwent primary TAA. Twenty patients with postoperative medial malleolar fractures >4 weeks postoperatively (cases) were identified. An additional 129 patients (controls) were randomly selected from the TAA database. Radiographic evaluation included tibial component coronal alignment and postoperative medial malleolar width. Demographics and radiographic variables were compared between cohorts. Logistic regression was used to investigate the association between medial malleolar fracture and postoperative coronal alignment, medial malleolar width, and prophylactic fixation of the medial malleolus. Mean (SD) medial malleolar width was significantly smaller in the fracture cohort (8.52 mm [1.6]) than in the control group (11.78 mm [1.74]) (P < .001). Mean (SD) tibial component coronal alignment was 92.17 degrees (2.77) in the fracture cohort and 90.21 degrees (1.66) in the control group (P = .002). Regression analysis identified a significant negative association between postoperative medial malleolar width and the probability of fracture (OR = 0.06, 95% CI 0.01, 0.26, P < .001). Varus malalignment of the tibial component was positively associated with the probability of fracture (OR = 1.90, 95% CI 1.27, 2.86, P = .002). Prophylactic screw fixation resulted in more than 90% reduction in the odds of a fracture (OR = 0.04, 95% CI 0.01, 0.45, P = .01). ROC curve analysis determined a medial malleolar width of 10.3 mm as a potential threshold for predicting fracture. Decreased medial malleolar width and postoperative varus malalignment were associated with an increased risk of postoperative medial malleolar fracture. Therefore, surgeons should consider prophylactic screw fixation in patients with a medial malleolar width <10.3 mm or at risk of postoperative varus deformity.

Kinematic Alignment Achieves a More Balanced Total Knee Arthroplasty Than Mechanical Alignment among CPAK Type I Patients: A Simulation Study

Background: There is no consensus on whether mechanical alignment (MA) or kinematic alignment (KA) should be chosen for total knee arthroplasty (TKA) for coronal plane alignment of the knee (CPAK) Type I with a varus arithmetic HKA (aHKA) and apex distal joint line obliquity (JLO). The aim of this study was to investigate whether MA or KA is preferable for soft tissue balancing in TKA for this phenotype. Method: This prospective cohort study included 64 knees with CPAK Type I osteoarthritis that had undergone cruciate-retaining TKA. Using optical tracking software, we simulated implant placement in the Mako system before making the actual bone cut and compared the results between MA and KA. Extension balance (the difference between medial and lateral gaps in extension) and medial balance (the difference in medial gaps in flexion and extension) were examined. These gap differences within 2 mm were defined as good balance. Achievement of overall balance was defined as an attainment of good extension and medial balance. The incidence of balance in each patient was compared with an independent sample ratio test. Results: Compared with the MA group, the KA group achieved better soft tissue balance in extension balance (p &lt; 0.001). A total of 75% of the patients in the KA group achieved overall balance, which was greater than the 38% achieved in the MA group (p &lt; 0.001). Conclusions: In robot-assisted TKA for CPAK Type I osteoarthritis, KA achieved knee balance during extension without soft tissue release in a greater percentage of patients than MA.

Influence of variable hinge positioning on coronal and sagittal alignment in uniplanar medial open-wedge high tibial osteotomy.

There is a high risk of increasing the posterior tibial slope (PTS) during medially opening-wedge high tibial osteotomy (mowHTO). Most recently, the idea of intentional simultaneous coronal and sagittal correction, using uniplanar cutting techniques has emerged. This study aims to examine the influences of variable hinge positioning and osteotomy gap height on the sagittal and coronal plane. Twenty uniplanar mowHTOs were performed in standardised (left) solid-foam proximal tibia models. In the different models, hinge position was rotated stepwise by 10°, between 90° (cutting straight medial to lateral) and 0° (cutting straight anterior to posterior) (n = 10). Additionally, gap heights of 5 and 10 mm were produced and analysed. Logistic regression analysis was performed to calculate a predictive regression formula for the relation between gap height, hinge rotation and the changes of medial proximal tibia angle (MPTA), medial and lateral PTS. Between cutting angles of 90 and 20°, the MPTA was mainly influenced by the gap height (0.95° MPTA per 1 mm gap height), but not by the cutting angle. Between 20 and 0°, the MPTA was decreased by 3.6° per 10° of rotation, but not by the gap height. Between cutting angles of 90 and 10°, the PTS was increased linearly by 0.97° per 10° of rotation and by 0.61° per 1 mm gap height. In mowHTO with lateral hinge positions, the MPTA is mainly influenced by gap height. Changes of PTS can be avoided by a straight lateral hinge position. In posterior hinge locations (0-20°), changes of MPTA are mainly caused by hinge rotation, but not by gap height. Level III, Case-control study.

Three-Dimensional Bowing Measurement of Distal Femur at Actual Size and Clinical Implications of Total Knee Arthroplasty.

Background and Objectives: To assess femoral shaft bowing (FSB) in coronal and sagittal planes and introduce the clinical implications of total knee arthroplasty (TKA) by analyzing a three-dimensional (3D) model with virtual implantation of the femoral component. Materials and Methods: Sixty-eight patients (average age: 69.1 years) underwent 3D model reconstruction of medullary canals using computed tomography (CT) data imported into Mimics® software (version 21.0). A mechanical axis (MA) line was drawn from the midportion of the femoral head to the center of the intercondylar notch. Proximal/distal straight centerlines (length, 60 mm; diameter, 1 mm) were placed in the medullary canal's center. Acute angles between these centerlines were measured to assess lateral and anterior bowing. The acute angle between the distal centerline and MA line was measured for distal coronal and sagittal alignment in both anteroposterior (AP) and lateral views. The diameter of curve (DOC) along the posterior border of the medulla was measured. Results: The mean lateral bowing in the AP view was 3.71°, and the mean anterior bowing in the lateral view was 11.82°. The average DOC of the medullary canal was 1501.68 mm. The average distal coronal alignment of all femurs was 6.40°, while the distal sagittal alignment was 2.66°. Overall, 22 femurs had coronal bowing, 42 had sagittal bowing, and 15 had both. Conclusions: In Asian populations, FSB can occur in coronal, sagittal, or both planes. Increased anterolateral FSB may lead to cortical abutment in the sagittal plane, despite limited space in the coronal plane. During TKA, distal coronal alignment guides the distal femoral valgus cut angle, whereas distal sagittal alignment aids in predicting femoral component positioning to avoid anterior notching. However, osteotomies along the anterior cortical bone intended to prevent notching may result in outliers due to differences between the distal sagittal alignment and the distal anterior cortical axis.

Trochlea morphology demonstrates variability but no gender difference in osteoarthritic patients undergoing total knee arthroplasty

BackgroundIn recent years, coronal lower leg alignment has received significant attention. Two classifications recently described the variability in both femoral and tibial morphology, resulting in differing native lower limb alignment.The native trochlea and the variability in morphology has received less attention. MethodsThis is a prospective cohort study of 200 patients undergoing robotically assisted TKA. Preoperative transverse CT scans were used to determine the posterior condylar axis (PCA), transepicondylar axis (TEA), lateral trochlear inclination (LTI), the sulcus angle (SA) and the anterior trochlear line (ATL). Outliers were defined as values > 1.5 IQR from median value. Trochlea dysplasia was defined as LTI < 12°. Gender differences were compared. ResultsIn total, 99 patients were female (49.4%). SA had a median of 137.0° (IQR 12°), ATL 4° (IQR 4), LTI 18° (IQR 7°). Median TEA-PCA was 5° external (IQR 3°). There were 5.0% outliers in SA, 3.0% of outliers in ATL, 3.5% outliers in LTI and 4.5% outliers in the TEA-PCA. Trochlear dysplasia was present in 11.5% of the measurements. There was no difference in any of the angles between the genders. ConclusionThe present study demonstrates no difference in trochlea morphology between the genders, rather a significant number of overall outliers in trochlear morphology. Larger cohorts but also, more investigations, are needed to better understand the trochlear morphology of patients undergoing total knee arthroplasty. The personalized alignment strategies and implants need to account for this variability in the population.