Effects of total knee arthroplasty on ankle alignment in patients with varus gonarthrosis: Do we sacrifice ankle to the knee?

Comparison of functional recovery of the knee following total knee arthroplasty in patients with and without ankle symptoms

BACKGROUND

Total knee arthroplasty (TKA) aims to restore motion and alleviate pain, enabling patients to return to daily activities. Despite advances in implants, surgery, and perioperative care, patient dissatisfaction rates remain significant.

AIM

To determine whether ankle symptoms are associated with inferior results of functional recovery of the knee following TKA.

METHODS

This prospective study included all patients with advanced knee osteoarthritis who underwent a primary unilateral TKA between August 2019 and December 2019 with data documented by the treating surgeon and outpatient physical therapists. Patients were categorized based on ankle symptoms using the American Orthopaedic Foot and Ankle Society (AOFAS) score: (1) Group 1 (AOFAS ≤ 85, n = 30); and (2) Group 2 (AOFAS > 85, n = 49). Active range of motion (ROM), the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the visual analogue scale (VAS) were compared between two groups.

RESULTS

Postoperative KOOS, ROM, and VAS significantly improved in both groups (P < 0.001). However, at three months, KOOS (P = 0.02) and extension motion (P = 0.01) improvements were significantly greater in group 2.

CONCLUSION

These findings suggest that preoperative ankle symptoms may negatively impact early knee functional recovery, particularly in KOOS scores and extension motion.

Comparative effects of mechanical and functional alignment in bilateral robotic total knee arthroplasty: a randomized controlled trial

BACKGROUND

Functional alignment (FA) in total knee arthroplasty (TKA) can achieve soft tissue balance by fine-tuning adjustments of bony resections and component alignment with less soft tissue release. However, joint line orientation relative to the floor in the knee and ankle after TKA is not well studied.

METHODS

A randomized-controlled trial was performed in 30 patients with robotic-assisted bilateral TKA using FA and mechanical alignment (MA) in the same patient. The outcome measures were as follows: (1) standing radiographic knee and ankle alignment; (2) clinical outcomes at 1, 3 and 6 months postoperatively (including forgotten joint score (FJS), KOOS, knee range of motion); (3) patient satisfaction score; and (4) soft tissue release.

RESULTS

Postoperative hip-knee-ankle angles between the FA and MA groups were similar (2.4° versus 2.4°, P = 0.952). Knee joint line orientation was significantly more parallel to the floor in the FA group (3.0° versus 4.7°, P < 0.001). There was no significant difference in ankle joint line orientation relative to the floor in the FA and MA groups (91.0° versus 92.4°, P = 0.099 for tibial plafond inclination and 92.5° versus 93.2°, P = 0.564 for talar dome inclination). However, in knees with preoperative varus with apex distal joint line orientation (coronal plane alignment of the knee (CPAK) classification type I), FA significantly achieved a more parallel knee and ankle joint line orientation relative to the floor (3.1° versus 5.1°, P = 0.002 for knee and 91.0° versus 93.5°, P = 0.028 for tibial plafond inclination). FA can obtain a balanced knee with significantly lower posteromedial releases (23.3% versus 76.7%, P < 0.001), with no superficial MCL release needed (0% versus 6.67%, P < 0.01). The FA group achieved significantly higher FJS at 3 months (53.3 versus 46.0, P = 0.015) and 6 months (67.8 versus 57.8, P < 0.001) with a higher patient satisfaction score (79.2 versus 84.3, P = 0.001).

CONCLUSION

Functional alignment can control the overall lower limb alignment similarly to mechanical alignment, with a knee joint line more parallel to the floor. Additionally, the ankle joint line was more parallel in knees with CPAK type I. FA can also provide a more balanced knee with less soft tissue release, a higher functional score, and greater patient satisfaction compared to mechanical alignment.

Ankle alignment before and after total knee arthroplasty in patients with valgus knee deformity

BACKGROUND

The impact of Total Knee Arthroplasty (TKA) on the biomechanics of bilateral ankle joints with valgus knees remains unclear. This study aimed to evaluate how unilateral TKA affects bilateral ankle tilt, limb alignment, and biomechanics in knee valgus.

METHODS

Among 105 patients with end-stage knee osteoarthritis and mild-to-moderate valgus deformity who underwent TKA between January 2021 and June 2023, 86 were included in the study retrospectively. The hip-knee-ankle angle (HKA), weight-bearing line ratio (WBLR), knee joint line convergence angle (KJLCA), knee joint line obliquity (KJLO), tibial anterior surface angle (TAS), tibial plafond inclination (TPI), talar inclination (TI), and tibiotalar tilt (TT) were measured on standing full-length lower limb radiographs preoperatively and postoperatively, with postoperative follow-up averaging 10.4 months. Patients were divided into Group A (0°~5°, 25 knees), Group B (5°~10°, 40 knees), and Group C (10°~15°, 21 knees) based on the degree of lower limb alignment correction. Additionally, patients were classified into contralateral knee varus (30 knees) and valgus (56 knees) groups based on the preoperative HKA angle of the contralateral knee.

RESULTS

With changes in HKA, both TAS and TT showed concurrent change. Postoperative TAS [93.2 (86.9, 116.8)] and TT [-0.4 ( -5.9, 8.1)] showed a significant increase in absolute value compared to preoperative TAS [90.3 (83.1, 100.5)] and TT [0.2 ( -5.2, 6.4)] (P < 0.05). This suggests that TKA may alter the inclination angle of the talar articular surface by correcting the lower limb mechanical axis. Postoperative comparisons of ΔTPI and ΔTI across correction groups revealed statistically significant differences (P < 0.05). These findings indicate that greater knee deformity is associated with a larger preoperative angle between the distal tibial articular surface and the horizontal plane. Correction of severe deformities increases the postoperative TI angle, leading to a more inclined talar articular surface. No correlation was observed between preoperative and postoperative HKA and alignment of the contralateral ankle joint.

CONCLUSION

Before and after TKA, concurrent changes were observed in the ipsilateral ankle's inclination angle. For severe knee valgus deformities, maintaining a residual valgus deformity postoperatively should be considered to avoid postoperative ankle complications.

Knee osteotomies significantly influence coronal ankle alignment: A radiographic analysis

Purpose

This study aimed to evaluate the effect of lateral closing-wedge high tibial osteotomy (LCW-HTO) and medial closing-wedge distal femoral osteotomy (MCW-DFO) on tibio-talar inclination (TTI) and Mikulicz lateral distal tibial angle (M-LDTA). We hypothesized that knee osteotomies significantly alter ankle coronal alignment by modifying TTI and distal tibial alignment in relation to the mechanical axis.

Methods

A retrospective radiographic analysis was conducted on 60 knees from 52 patients (37 LCW-HTO and 23 MCW-DFO) treated between 2006 and 2020. Inclusion criteria included full-length weight-bearing radiographs pre- and post-operatively, no prior ipsilateral lower limb surgery, absence of shaft deformities or advanced ankle osteoarthritis (Takakura grade >1), and age ≥16 years with ≥2 years of follow-up. Radiographic parameters measured included LDTA, hip-knee-ankle angle, M-LDTA and TTI, with ankle realignment quantified through differences between LDTA and M-LDTA and between pre- and post-operative TTI.

Results

In the MCW-DFO group, the difference between LDTA and M-LDTA decreased from 3.5 ± 2.3° to 1.3 ± 1.1° (p < 0.0001), indicating improved alignment. The LCW-HTO group showed a smaller but significant reduction from 4.5 ± 1.8° to 2.2 ± 1.7° (p < 0.0001). TTI improved significantly in both groups, with a greater adjustment in MCW-DFO (ΔTTI = 7.0 ± 4.3°, p < 0.01) compared to LCW-HTO (ΔTTI = 4.2 ± 2.7°, p < 0.01). The difference between LDTA and TTI decreased in both groups, reflecting post-operative convergence of the mechanical and anatomical axes.

Conclusion

Knee osteotomies significantly influence ankle coronal alignment, particularly modifying TTI and M-LDTA. Higher-level osteotomies (MCW-DFO) exert a greater effect on ankle alignment than LCW-HTO. Preoperative valgus or varus knee deformities must be carefully evaluated to anticipate post-operative ankle imbalance. Surgeons should assess full-length radiographs to prevent unintended malalignment.

Level of Evidence

Level III.

Factors influencing ankle alignment changes following medial unicompartmental knee arthroplasty: Preoperative knee and ankle deformities and extent of knee alignment correction

INTRODUCTION

The impact of medial unicompartmental knee arthroplasty (MUKA) on ankle alignment is not well-studied. This study aims to investigate the changes in ankle alignment following MUKA and identify the influencing factors.

MATERIALS AND METHODS

A retrospective analysis included 175 patients undergoing MUKA between 2018 and 2020. Patients were categorized into varus (n =  113) or valgus (n =  62) ankle groups based on preoperative ankle deformities. Preoperative and postoperative full-length standing radiographs were used for radiographic measurements.

RESULTS

Following MUKA, significant differences in the change in tibial plafond-talus angle (PTA) were observed between the groups, with the varus ankle group showing a change of -0.71 ±  0.82° and the valgus ankle group showing a change of 0.08 ±  0.94° (p <  0.001). In the varus ankle group, the tibial plafond-ground angle (PGA) increased from -3.65 ±  4.22° preoperatively to -0.51 ±  4.52° postoperatively (p <  0.001), talus-ground angle (TGA) increased from -5.28 ±  4.32° to -1.32 ±  4.74° (p <  0.001), and PTA decreased from 1.52 ±  1.04° to 0.81 ±  1.12° (p <  0.001). In the valgus ankle group, PGA increased from -5.44 ±  4.39° to -1.43 ±  4.63° (p <  0.001) and TGA increased from -4.55 ±  4.24° to -0.59 ±  4.47° (p <  0.001), but PTA did not show a significant change. Ankle alignment change significantly correlated with preoperative joint line convergence angle (JLCA), preoperative medial proximal tibial angle (MPTA), preoperative PGA, preoperative TGA, preoperative PTA, hip-knee-ankle angle (HKA) changes, and bearing thickness.

CONCLUSIONS

MUKA significantly corrects the majority of ankle alignment towards a more neutral position. The extent of ankle alignment correction is influenced by preoperative knee and ankle joint deformities, as well as the degree of knee alignment correction.

Robotic functional alignment in knee arthroplasty minimizes impact on ankle alignment: Role of MPTA and LDFA preservation

PURPOSE

Alignment strategies in knee arthroplasty have a profound influence not only on knee biomechanics but also on the biomechanics of adjacent joints, particularly the ankle. Functional alignment (FA) represents a flexible alignment strategy aimed at achieving patient-specific balance. However, predefined boundaries are often applied to ensure mechanical stability, leading to adjustments in the medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA) while still respecting the patient's native alignment as much as possible. FA is a patient-specific strategy that seeks to respect the patient's preoperative phenotype or constitutional alignment while achieving a balanced and stable knee. The hypothesis is that FA strategies can protect the ankle from excessive biomechanical stress.

METHODS

A retrospective cohort analysis was conducted on 300 consecutive patients who underwent robotic-assisted knee arthroplasty. Preoperative and 6-month post-operative radiographic evaluations measured key ankle parameters, tibial plafond inclination (TPI), talar inclination (TI) and Talar Tilt (TT). Statistical analyses evaluated the influence of alignment strategies on these parameters, with particular focus on whether MPTA and LDFA crossed the 90° threshold, indicating a shift from varus to valgus or vice versa.

RESULTS

FA demonstrated smaller changes in ankle parameters compared to mechanical alignment (MA). In the FA group, mean changes were 1.8° for KTPA (standard deviation [SD] = 1.1°, p = 0.03), 2.4° for TPI (SD = 1.0°, p = 0.04), 2.1° for TI (SD = 1.3°, p = 0.05) and 1.7° for TT (SD = 0.9°, p = 0.04). The MA group showed greater deviations: 3.9° for KTPA (SD = 1.5°, p = 0.01), 5.2° for TPI (SD = 1.2°, p = 0.02), 4.8° for TI (SD = 1.4°, p = 0.03) and 3.6° for TT (SD = 1.1°, p = 0.04). Alterations in LDFA and MPTA exceeding 2° were significantly associated with worsening ankle alignment. Furthermore, FA, with its goal of maintaining Coronal Plane Alignment of the Knee (CPAK) classification, was associated with minimal modifications to ankle angles, suggesting potential biomechanical benefits as reported in the literature.

CONCLUSIONS

FA was associated with smaller changes in ankle alignment parameters, indicating its ability to better preserve native joint positioning. Future research should focus on longitudinal studies to confirm these benefits and further establish the FA strategy as a standard in knee arthroplasty, particularly its capacity to maintain CPAK classification alignment.

LEVEL OF EVIDENCE

Level III.

Medial opening low tibial osteotomy shifts the load laterally not only at the ankle joint but also at the knee joint

Purpose

The purpose of this study was to determine the effects of medial opening low tibial osteotomy (LTO) on lower limb alignment, including the knee joint, 1 year after low tibial osteotomy.

Methods

This study included 20 legs of 20 patients (mean age, 66.8 ± 5.4 years) who underwent LTO for medial ankle osteoarthritis and evaluated the changes in the hip-knee-ankle angle (HKA), percentage hip-to-ankle line (%HA), percentage hip-to-calcaneal line (%HC), medial proximal tibial angle (MPTA), knee joint line convergence angle (K-JLCA), tibio-calcaneal angle (TCA), tibial anterior surface angle (TAS), tibio-plafond inclination (TPI), talar inclination (TI), ankle joint line convergence angle (A-JLCA), mechanical ankle joint axis point (MAJAP) on radiographs and the Japanese Society for Surgery of the Foot (JSSF) ankle/hindfoot scale before and 1 year after low tibial osteotomy.

Results

The mean preoperative/postoperative measured values showed the following: HKA (degrees) of 1.0 ± 3.7/-0.8 ± 3.7; %HC of 38.8 ± 10.0/53.8 ± 16.1; MPTA (degrees) of 85.6 ± 2.4/87.6 ± 2.1; and A-JLCA (degrees) of 4.2 ± 2.9/1.1 ± 2.3 respectively. Including other measurements, a significant increase in the %HA, %HC, MPTA, TCA, TAS, MAJAP and JSSF ankle/hindfoot scale was observed postoperatively, whereas a significant decrease in the HKA, TPA, TI and A-JLCA was observed postoperatively (p < 0.05). With the numbers available, no significant differences were observed between the preoperative and postoperative values of K-JLCA (n.s.).

Conclusion

After LTO, the entire lower limb alignment became valgus, and the loading points of the knee and ankle joints shifted laterally. These changes must be considered when performing LTO, especially in patients with lateral knee OA.

Level of Evidence

Ⅳ.

Varus knee osteoarthritis with ankle osteoarthritis demonstrates greater hindfoot inversion and larger ankle inversion loading during gait following total knee arthroplasty compared to varus knee osteoarthritis alone

PURPOSE

Although patients with varus knee osteoarthritis (KOA) and concurrent ankle osteoarthritis (AOA) may experience increased ankle joint pain after total knee arthroplasty (TKA), the underlying mechanism remains unclear. This study aimed to investigate the effects of concurrent AOA on ankle and hindfoot alignment, frontal plane ankle and hindfoot biomechanics during gait following TKA and the clinical outcomes.

METHODS

Twenty-four patients with varus KOA who underwent TKA were included in this retrospective cohort study. Patients were categorized into two groups: with and without AOA. Radiographic evaluations of lower-limb, ankle and hindfoot alignment, and knee and ankle clinical outcomes were conducted preoperatively and 6 months postoperatively. In addition, gait analyses were performed to investigate knee, ankle and hindfoot kinematics and kinetics. Each data was compared between patients with and without AOA.

RESULTS

Concomitant AOA was found in eight ankles. The AOA group exhibited greater postoperative hindfoot varus and increased postoperative ankle pain than the non-AOA group. Gait analysis showed no significant differences in knee varus alignment or tibial tilt after TKA between the groups. However, the AOA group demonstrated significantly greater hindfoot inversion and larger ankle inversion loading.

CONCLUSION

One third of patients who underwent TKA had concurrent AOA associated with hindfoot varus. Despite achieving proper coronal knee alignment postoperatively, these patients experienced greater hindfoot and ankle joint inversion load during gait. Surgeons should consider the inability to evert the hindfoot and the possibility of increased ankle joint pain when planning and performing TKA.

LEVEL OF EVIDENCE

Level III.

Preoperative Hindfoot Alignment and Outcomes After High Tibial Osteotomy for Varus Knee Osteoarthritis: We Walk on Our Heel, Not Our Ankle

UPDATE

This article was updated on May 15, 2024 because of previous errors, which were discovered after the preliminary version of the article was posted online. On page 898, in the section entitled "Materials and Methods," the sentence that had read "The WBL ratio of the knee joint was defined as the point where the GA or MA passed through the width of the tibia and intersected a line from the center of the femoral head to the center of the calcaneus (for the GA) or talus (for the MA), with the medial edge defined as 0% and the lateral edge as 100%." now reads "The WBL ratio of the knee joint was defined as the point where the GA or MA passed through the width of the tibia and intersected a line from the center of the femoral head to the lowest point of the calcaneus (for the GA) or the center of the talus (for the MA), with the medial edge defined as 0% and the lateral edge as 100%." Likewise, in the legend for Figure 3 on page 899, the sentence that had read "Depiction of the ground mechanical axis (GA), defined as the line (represented by the solid red line) from the center of the femoral head to the ground reaction point at the center of the calcaneus, passing lateral to the traditional mechanical axis (MA; represented by the dashed red line)." now reads "Depiction of the ground mechanical axis (GA), defined as the line (represented by the solid red line) from the center of the femoral head to the ground reaction point at the lowest point of the calcaneus, passing lateral to the traditional mechanical axis (MA; represented by the dashed red line)." Finally, on page 903, "HKA" was changed to "HKA angle" in Table III.

BACKGROUND

The hip-to-calcaneus axis, previously known as the ground mechanical axis (GA), ideally passes through the center of the knee joint in the native knee. The aim of this study was to elucidate, with use of hip-to-calcaneus radiographs, changes in knee and hindfoot alignment and changes in outcomes following high tibial osteotomy (HTO).

METHODS

We reviewed the records for 128 patients who underwent HTO between 2018 and 2020. Patients were stratified into 2 groups, a hindfoot valgus group (n = 94) and a hindfoot varus group (n = 34), on the basis of their preoperative hindfoot alignment. The hindfoot alignment was evaluated with use of the hindfoot alignment angle (HAA). To evaluate lower-limb alignment, full-length standing posteroanterior hip-to-calcaneus radiographs were utilized to measure 4 radiographic parameters preoperatively and 2 years postoperatively: the hip-knee-ankle (HKA) angle, hip-knee-calcaneus (HKC) angle, and the weight-bearing line (WBL) ratios of the mechanical axis (MA) and GA.

RESULTS

The mean HAA improved significantly from 5.1° valgus preoperatively to 1.9° valgus postoperatively in the hindfoot valgus group (p < 0.001). In contrast, in the hindfoot varus group, the HAA showed no meaningful improvement in the coronal alignment of the hindfoot following HTO (p = 0.236). The postoperative mean HKC angle in the hindfoot varus group was 2° more varus than that in the hindfoot valgus group (1.0° versus 3.0°; p = 0.001), and the GA in the hindfoot varus group passed across the knee 8.0% more medially than that in the hindfoot valgus group (55% versus 63% from the most medial to the most lateral part of the tibial plateau). The hindfoot varus group had worse postoperative clinical outcomes than the hindfoot valgus group in terms of the mean Knee injury and Osteoarthritis Outcome Score for pain and American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Score.

CONCLUSIONS

Although our findings did not provide sufficient evidence to establish clinically relevant differences between the groups, they indicated that the group with a preoperative fixed hindfoot varus deformity had a higher rate of undercorrection and worse clinical outcomes, especially pain, following HTO. Therefore, modification of the procedure to shift the GA more laterally may be required for these patients.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Weight-bearing line at the ankle joint level shifted laterally after total knee arthroplasty for varus knee osteoarthritis: Evaluation of the hip-to-calcaneus line

BACKGROUND

Few studies have comprehensively examined how alignment beyond the ankle joint changes after Total knee arthroplasty (TKA). This retrospective study aimed to answer the questions: (1) do the radiological parameters beyond the ankle joint, including the weight-bearing line at the ankle joint level, change after TKA in varus knee osteoarthritis? (2) Does the lower extremity alignment correlate with alignment beyond the ankle joint?

HYPOTHESIS

Our hypothesis was that TKA altered the radiological parameters beyond the ankle, which correlated with the lower extremity alignment.

PATIENTS AND METHODS

This retrospective study included 67 patients who underwent mechanically aligned TKA for varus knee osteoarthritis. The hip-knee-ankle angle (HKA), tibial plafond inclination angle (TPIA), hindfoot alignment angle (HA), talar tilt (TT), and weight-bearing line at the ankle joint level (mechanical ankle joint axis point [MAJAP]) were measured using radiographs taken before and 6 months after TKA; each parameter was compared between the two time points. The correlations between HKA and other parameters were examined preoperatively and postoperatively.

RESULTS

The mean HKA, TPIA, HA, TT, and MAJAP changed significantly after TKA from 15.0±6.1̊ to 2.6̊±3.5̊, from 10.8̊±5.7̊ to 4.7̊±3.9̊, from 2.3̊±5.5̊ to -2.5̊±4.5̊, from 0.2̊±1.3̊ to -0.5̊±1.4̊, and from 29.3±23.3 to 54.3±20.6, respectively. Correlations were noted between the preoperative HKA and the preoperative TPIA (r=0.58), HA (r=0.36), and MAJAP (r=-0.59), and between the postoperative HKA and the postoperative TPIA (r=0.54) and MAJAP (r=-0.38).

DISCUSSION

TKA for varus knee osteoarthritis altered radiological parameters beyond the ankle, with the weight-bearing line at the ankle joint level passing more laterally. The weight-bearing line at the ankle joint level was correlated with lower extremity alignment both preoperatively and postoperatively.

LEVEL OF EVIDENCE

IV; single-centre retrospective observational study.

Increased ankle pain after total knee arthroplasty is associated with a preoperative lateralized gait and talar tilt, but not with ankle laxity or the range of motion of the subtalar joint

Aims

Total knee arthroplasty (TKA) may provoke ankle symptoms. The aim of this study was to validate the impact of the preoperative mechanical tibiofemoral angle (mTFA), the talar tilt (TT) on ankle symptoms after TKA, and assess changes in the range of motion (ROM) of the subtalar joint, foot posture, and ankle laxity.

Methods

Patients who underwent TKA from September 2020 to September 2021 were prospectively included. Inclusion criteria were primary end-stage osteoarthritis (Kellgren-Lawrence stage IV) of the knee. Exclusion criteria were missed follow-up visit, post-traumatic pathologies of the foot, and neurological disorders. Radiological angles measured included the mTFA, hindfoot alignment view angle, and TT. The Foot Function Index (FFI) score was assessed. Gait analyses were conducted to measure mediolateral changes of the gait line and ankle laxity was tested using an ankle arthrometer. All parameters were acquired one week pre- and three months postoperatively.

Results

A total of 69 patients (varus n = 45; valgus n = 24) underwent TKA and completed the postoperative follow-up visit. Of these, 16 patients (23.2%) reported the onset or progression of ankle symptoms. Varus patients with increased ankle symptoms after TKA had a significantly higher pre- and postoperative TT. Valgus patients with ankle symptoms after TKA showed a pathologically lateralized gait line which could not be corrected through TKA. Patients who reported increased ankle pain neither had a decreased ROM of the subtalar joint nor increased ankle laxity following TKA. The preoperative mTFA did not correlate with the postoperative FFI (r = 0.037; p = 0.759).

Conclusion

Approximately one-quarter of the patients developed ankle pain after TKA. If patients complain about ankle symptoms after TKA, standing radiographs of the ankle and a gait analysis could help in detecting a malaligned TT or a pathological gait.

Foot and/or ankle problems following limb alignment changes in uni-compartmental knee arthroplasty

Objective

Foot and/or ankle (F/A) problems may be encountered in medial uni-compartmental knee (UKA) patients postoperatively due to the limb alignment changes and alterations in weight bearing of F/A. This study aimed to evaluate the risk factors and the incidence of foot and ankle (F/A) problems in (UKA) arthroplasty patients.

Methods

Patients who underwent UKA between 2016 and 2019 in our clinic were evaluated and the presence of F/A problems was recorded. Radiologic evaluations included hip knee ankle angle (HKA), medial proximal tibial angle, posterior tibial slope angle, talar tilt angle, talar inclination, talar dome to mechanical axis (TDMA), and talocrural angle (TCA) measured on preoperative and follow-up long-leg standing radiographs. The range of motion, Q angles, and muscle strengths were measured. Visual analog scale, physical performance limitations, and patient-reported activity limitations were evaluated for all patients. Patients with reported F/A problems were additionally evaluated with Foot Functional Index.

Results

Forty-four patients (38 female, 6 male; mean age 58.66 ± 8.6 years; mean BMI 31.30 ± 3.81, mean follow-up period 34.22 ± 18.95 months) were included in the study. There were 13 patients (29.5%) with reported F/A problems. Postoperative comparison of patients with and without F/A problems showed statistically significant differences in only WOMAC and SF12 physical health sub-scores ( p = 0.002, p = 0.003, respectively). There was no significant postoperative change in TDMA in patients with F/A problems ( p > 0.05) in contrast to patients without F/A problems ( p = 0.006). There was no statistically significant difference in preoperative TCA measurements between groups ( p = 0.79). Comparison of knee and ankle radiologic measurements between groups demonstrated significant difference only in postoperative HKA measurements (−2.82 ± 2.53 vs. −0.80 ± 3.12, p = 0.033).

Conclusion

F/A problems adversely affecting the functional status were frequent in our cohort of UKA patients. Postoperative residual varus deformity may be a risk factor for this. Therefore, if slight varus alignment is aimed at UKA patients, preoperative F/A status should be evaluated.

Functional gait analysis reveals insufficient hindfoot compensation for varus and valgus osteoarthritis of the knee

PURPOSE

The hindfoot is believed to compensate varus and valgus deformities of the knee by eversion and inversion movements. But these mechanisms were merely found in static radiologic measurements. The aim of this study was, therefore, to assess dynamic foot posture during gait using pressure-sensitive wireless insoles in patients with osteoarthritis of the knee and frontal knee deformities.

METHODS

Patients with osteoarthritis of the knee were prospectively included in this study. Patients were clinically and radiologically (mechanical tibiofemoral angle (mTFA), hindfoot alignment view angle (HAVA), and talar tilt (TT)) exa mined. Gait line analysis was conducted using pressure-sensitive digital shoe insoles.

RESULTS

Eighty-two patients (varus n = 52, valgus n = 30) were included in this prospective clinical study. Radiologically, the mTFA significantly correlated with the HAVA (cor = -0.72, p < 0.001) and with the TT (Pearson's cor = 0.32, p < 0.006). Gait analysis revealed that the gait lines in varus knee osteoarthritis were lateralized, despite the hindfoot valgus. In valgus knee osteoarthritis, gait lines were medialized, although the hindfoot compensated by varization.

CONCLUSIONS

Functional dynamic gait analysis could demonstrate that the hindfoot is not able to sufficiently compensate for frontal malalignments of the knee joint, contrary to static radiologic findings. This led to a narrowing of the joint space of the ankle medially in varus and laterally in valgus knee osteoarthritis.

The impact of different alignment strategies on bone cuts in total knee arthroplasty for varus knee phenotypes

PURPOSE

The purpose of this study was to visualise the influence of alignment strategy on bone resection in varus knee phenotypes. The hypothesis was that different amounts of bone resection would be required depending on the alignment strategy chosen. Through visualisation of the corresponding bone sections, it was hypothesised, it would be possible to assess which of the different alignment strategies would require the least amount of change to the soft tissues for the chosen phenotype, whilst still ensuring acceptable alignment of the components, and thus could be considered the most ideal alignment strategy.

METHODS

Simulations of the different alignment strategies (mechanical, anatomical, constrained kinematic and unconstrained kinematic) in relation to their bone resections were performed on five common exemplary varus knee phenotypes. VAR_HKA174° VAR_FMA87° VAR_TMA84°, VAR_HKA174° VAR_FMA90° NEU_TMA87°, VAR_HKA174° NEU_FMA93° VAR_TMA84°, VAR_HKA177° NEU_FMA93° NEU_TMA87° and VAR_HKA177° VAL_FMA96° VAR_TMA81°. The phenotype system used categorises knees based on overall limb alignment (i.e. hip knee angle) but also takes into account joint line obliquity (i.e. TKA and FMA) and has been applied in the global orthopaedic community since its introduction in 2019. The simulations are based on long-leg radiographs under load. It is assumed that a change of 1° in the alignment of the joint line corresponds to a displacement of the distal condyle by 1 mm.

RESULTS

In the most common phenotype VAR_HKA174° NEU_FMA93° VAR_TMA84°, a mechanical alignment would result in an asymmetric elevation of the tibial medial joint line by 6 mm and a lateral distalisation of the femoral condyle by 3 mm, an anatomical alignment only by 0 and 3 mm, a restricted by 3 and 3 mm, respectively, whilst a kinematic alignment would result in no change in joint line obliquity. In the similarly common phenotype 2 VAR_HKA174° VAR_FMA90° NEU_TMA87° with the same HKA, the changes are considerably less with only 3 mm asymmetric height change on one joint side, respectively, and no change in restricted or kinematic alignment.

CONCLUSION

This study shows that significantly different amounts of bone resection are required depending on the varus phenotype and the alignment strategy chosen. Based on the simulations performed, it can, therefore, be assumed that an individual decision for the respective phenotype is more important than the dogmatically correct alignment strategy. By including such simulations, the modern orthopaedic surgeon can now avoid biomechanically inferior alignments and still obtain the most natural possible knee alignment for the patient.

The Relationship between Frontal, Axial Leg Alignment, and Ankle Joint Line Orientation-a Radiographic Analysis of Healthy Subjects

OBJECTIVE

Ankle joint line orientation (AJLO) is influenced by the subtalar foot and frontal leg alignment. However, the influence of axial leg alignment on AJLO remains unclear. The study aimed to analyze the influence of frontal, axial leg alignment on AJLO in healthy subjects.

METHODS

Thirty healthy subjects (60 legs) without prior surgery underwent standing biplanar long leg radiograph (LLR) between 2016 and 2020. AJLO was measured in standing long-leg radiographs relative to the ground. Meary's angle and calcaneal pitch were measured. Hip-knee-ankle angle (HKA), femoral antetorsion, and tibial torsion were assessed with SterEOS software (EOS Imaging, Paris, France). LLR was acquired with the feet directing straight anteriorly, which corresponds to a neutral foot progression angle (FPA). The influence of subtalar, frontal, and axial alignment on AJLO was analyzed in a multiple regression model.

RESULTS

An increase in knee valgus increased relative valgus AJLO by 0.5° (95% CI: 0.2° to 0.7°) per 1° (P < 0.001). A decrease in femoral antetorsion increased relative valgus AJLO by 0.2° (95% CI: 0.1° to 0.2°) per 1° (P < 0.001), whereas Meary's angle and calcaneal pitch did not influence AJLO.

CONCLUSION

A link between frontal, axial leg alignment, and AJLO could be demonstrated, indicating that a valgus leg alignment and relative femoral retrotorsion are associated with an increase of valgus AJLO in healthy subjects when placing their feet in a neutral position. Alteration of the frontal, or rotational profile after realignment surgery or by implant positioning might influence the AJLO, when the FPA is kept constant.

Evaluation of hindfoot and knee alignment by the hip-to-calcaneus view in patients with knee osteoarthritis and healthy individuals

BACKGROUND

Hip-to-calcaneus (HC) view is a whole-leg standing view that can visualize the hindfoot in detail. The aim of this study was to investigate the reliability and validity of tibiocalcaneal angle in HC view (H-TCA) by comparing it with that in long axial view (L-TCA). We also verified whether periarticular knee alignment parameters, measured conventionally in whole-leg standing radiography, could be measured in HC view.

METHOD

Sixty healthy volunteers and 61 patients with medial knee osteoarthritis were included. H-TCA was measured by two examiners in the healthy group, and intra-class correlation coefficients (ICCs) were evaluated. H-TCA and L-TCA were then measured in the healthy and osteoarthritis groups and correlated. Finally, we measured hip-knee-ankle angle, mechanical axis deviation ratio, mechanical lateral distal femoral angle, medial proximal tibial angle, and joint-line convergence angle in HC view and conventional whole-leg standing radiography to evaluate statistical differences and correlations.

RESULTS

The intra-observer and inter-observer ICCs were 0.86 and 0.76, respectively. Correlation coefficients (r) between H-TCA and L-TCA were r = 0.87 in healthy group and r = 0.81 in osteoarthritis group, indicating a strong positive correlation in both groups. There was no significant difference in periarticular knee alignment parameters between HC view and conventional whole-leg radiography.

CONCLUSIONS

Hindfoot evaluation in HC view showed high intra-observer and inter-observer reliabilities and strong positive correlation with TCA in long axial view. By using HC view before knee surgery, such as total knee arthroplasty, other necessary alignments can be evaluated simultaneously.

Increasing grades of frontal deformities in knee osteoarthritis are not associated with ligamentous ankle instabilities

PURPOSE

Varus or valgus deformities in knee osteoarthritis may have a crucial impact on ankle subtalar range of motion (ROM) and ligamentous stability. The purpose of this study was to assess whether the grade of ankle eversion and inversion rotation stability was influenced by frontal deformities of the knee joint.

METHODS

Patients who were planned to undergo total knee arthroplasty (TKA) were prospectively included in this study. Patients were examined radiologically (mechanical tibiofemoral angle (mTFA), hindfoot alignment view angle (HAVA), anterior distal tibia angle (ADTA)) and clinically (ROM of the knee and ankle joint, foot function index, knee osteoarthritis outcome score). Ankle stability was assessed using an ankle arthrometer (AA) to test inversion/eversion (ie) rotation and anterior/posterior (ap) displacement stability of the ankle joint. Correlations were calculated using Pearson's coefficient, and differences between two independent groups of nonparametric data were calculated using a two-sided Wilcoxon signed rank test.

RESULTS

Eighty-two (varus n = 52, valgus n = 30) patients were included. The preoperative mTFA significantly correlated with the HAVA (Pearson's correlation = - 0.72, p < 0.001). Laxity testing of the ankle demonstrated that in both varus and valgus knee osteoarthritis, higher grades of mTFA did not correlate with the inversion or eversion capacity of the ankle joint. The ADTA significantly correlated with the posterior displacement of the ankle joint (cor = 0.24, p = 0.049).

CONCLUSIONS

This study could not confirm that higher degrees of frontal knee deformities in osteoarthritis were associated with increasing grades of ligamentous ankle instabilities or a reduced ROM of the subtalar joint.

LEVEL OF EVIDENCE

II.

Radiographic analysis using the hip-to-calcaneus line and its association with lower limb joint kinetics in varus knee osteoarthritis

BACKGROUND

This study aimed to (1) determine whether the hip to ankle (HA) line or hip to calcaneus (HC) line better reflects knee coronal plane kinetics, (2) to examine whether the HC line reflects ankle coronal plane kinetics, and (3) to evaluate the radiological and biomechanical aspects of ankle in varus knee osteoarthritis (OA).

METHODS

Full-length, postero-anterior radiographs (hip-to-calcaneus radiographs) were taken and gait analysis was performed in 21 varus knee OA patients. The %HA where the HA lines pass through the tibial plateau, and the %HC and the mechanical ankle joint axis point (MAJAP), where the HC line passes through the tibial plateau and tibial plafond, respectively, were calculated. Knee adduction angular impulse (KAAI) and ankle inversion angular impulse (AIAI) were collected as kinetic data. Finally, we divided the patients into two groups with and without ankle OA, and compared each parameter between both groups.

RESULTS

The %HA and %HC were correlated with KAAI (%HA; r = -0.68, P = 0.001, %HC; r = -0.81, P < 0.001, respectively) and MAJAP was correlated with AIAI (r = -0.55, P = 0.009). MAJAP was significantly smaller, and KAAI and AIAI were significantly larger in the ankle OA group.

CONCLUSIONS

Radiographic analysis using the HC line was more strongly correlated to knee joint kinetics than the HA line and was also correlated to ankle joint kinetics. Assessing lower limb alignment using the HC line could be useful to evaluate the knee and ankle joints for varus knee OA.

Correction of severe valgus osteoarthritis by total knee arthroplasty is associated with increased postoperative ankle symptoms

PURPOSE

The aim of this study was to assess the mid-term clinical outcome of the ankle joint after total knee arthroplasty (TKA) in high-grade valgus osteoarthritis.

METHODS

In this case-control study, n = 36 patients with a preoperative mechanical tibiofemoral angle (mTFA) ≥ 15° who underwent TKA between December 2002 and December 2012 were included. The control group (mTFA < 15°) of n = 60 patients was created using case matching. Radiological [mechanical tibiofemoral angle (mTFA) and ankle joint orientation to the ground (G-AJLO)] and clinical parameters [Foot Function Index (FFI), Knee Society Score, Forgotten Joint Score, and Range of Motion (ROM)] were analysed. The mean follow-up time was 59 months (IQR [56, 62]).

RESULTS

The degree of correcting the mTFA by TKA significantly correlated with the postoperative FFI (R = 0.95, p < 0.05), although the knee and ankle joint lines were corrected to neutral orientations. A cut-off value of 16.5° [AUC 0.912 (0.85-0.975 95% CI), sensitivity = 0.8, specificity = 0.895] was calculated, above which the odds ratio (OR) for developing ankle symptoms increased vastly [OR 34.0 (9.10-127.02 95% CI)]. ROM restrictions of the subtalar joint displayed a strong significant correlation with the FFI (R = 0.74, p < 0.05), demonstrating that decreased ROM of the subtalar joint was associated with aggravated outcomes of the ankle joint.

CONCLUSIONS

In this study, higher degrees of leg axis correction in TKA were associated with increased postoperative ankle symptoms. When TKA is performed in excessive valgus knee osteoarthritis, surgeons should be aware that this might trigger the onset or progression of ankle symptoms, particularly in cases of a stiff subtalar joint.

LEVEL OF EVIDENCE

III.

A Retrospective Study of the Risk Factors for Postoperative Foot or Ankle Pain in 90 Patients with Varus Osteoarthritis of the Knee who Underwent Total Knee Arthroplasty

Background

The reasons for foot and ankle pain following total knee arthroplasty (TKA) for knee varus osteoarthritis are unknown. This retrospective study aimed to investigate the risk factors for postoperative foot and ankle pain in patients with varus osteoarthritis of the knee who underwent TKA.

Material/Methods

We enrolled 90 patients who underwent TKA for varus knee osteoarthritis. The visual analog scale (VAS) was used to evaluate patients’ foot or ankle pain before and after surgery. The correlation between independent variables (eg, age, sex, body mass index [BMI], ankle osteoarthritis, and varus angle) and foot and ankle pain in patients with osteoarthritis of the knee was measured. Moreover, radiological changes were compared between the groups with and without worsened pain.

Results

No significant difference in VAS was found between patients <60 and ≥60 years of age (P>0.05). Male sex and BMI <30 kg/m² were weakly correlated with preoperative foot or ankle pain. However, patients with varus of ≥6° and preexisting ankle osteoarthritis had a higher incidence of foot or ankle pain before surgery. Moreover, no significant differences in radiological changes were found between the groups with and without worsened foot or ankle pain after surgery (P>0.05).

Conclusions

In male patients with osteoarthritis of the knee, a BMI <30 kg/m², varus of <6°, and no preexisting ankle osteoarthritis were protective factors for foot and ankle pain. TKA corrected knee and ankle malalignment. Therefore, postoperative foot and ankle pain was not associated only with TKA surgery.

Clinical and Radiological Changes of Ankle in Knee Osteoarthritis With Varus After Total Knee Arthroplasty: A Systematic Review

Background: Arthritis with severe varus deformity remains a challenge in total knee arthroplasty (TKA). Until recently, surgeons aimed at a neutral lower limb alignment when performing a TKA. However, the impact of TKA on the ankle joint has been ignored. Therefore, we conducted a systematic review to assess the clinical and radiological changes in the ankle joint after TKA on knees with severe varus deformity. Methods: A systematic search was conducted in four English (PubMed, Embase, Cochrane Library, and Web of Science) and four Chinese (CBM, VIP, CNKI, and Wan Fang Database) databases. Screening of literature and extraction of data were independently performed by two researchers. The modified methodological index for non-randomized studies (MINORS) was used to assess the quality. Results: A total of eight studies were eligible, namely, four prospective and four retrospective studies. TKA resulted in a negative clinical effect in the ankle joint in patients with ankle osteoarthritis. Seven studies reported changes in the mechanical tibiofemoral angle, and four studies reported radiological changes in the hindfoot. The mean score of the MINORS was 9.8 out of eight (9-11). Conclusion: As a result of the correction of the knee osteoarthritis with severe varus deformity following mechanically aligned TKA, the radiological malalignment of the ankle joint was improved. However, some patients experience increased ankle pain after undergoing TKA, especially, if there was a residual knee varus deformity, a stiff hindfoot with varus deformity, or ankle arthritis.

Poor Correction Capacity of Preexisting Ankle Valgus Deformity after Total Knee Arthroplasty

This study investigated the differences in ankle alignment changes after TKA in patients with varying preexisting ankle deformities. We retrospectively examined 90 knees with osteoarthritis and varus deformity in 78 patients who underwent TKA. Preoperative and postoperative radiographic parameters were analyzed. According to their preexisting ankle deformity, patients were assigned to the valgus or varus group. Overall, 14 (15.6%) cases were of preoperative valgus ankle deformity; the remainder were of preoperative varus ankle deformity. Hip-knee-ankle angle (HKA), tibial plafond-ground angle (PGA), and talus-ground angle (TGA) all exhibited significant correction in both groups; however, tibial plafond-talus angle (PTA) and superior space of ankle joint (SS) only changed in the varus group. The median PTA and SS significantly decreased from 1.2° to 0.3° (p < 0.001) and increased from 2.5 to 2.6 mm (p = 0.013), respectively. Notably, ∆PTA positively correlated with ∆HKA in the varus group (r = 0.247, p = 0.032) but not in the valgus group. Between-group differences in postoperative PTA (p < 0.001) and ∆PTA (p < 0.001) were significant. The degree of ankle alignment correction after TKA differed between patients with preexisting varus and valgus ankle deformities. TKA could not effectively correct the preexisting ankle valgus malalignment.

Hindfoot Alignment Change After Total Ankle Arthroplasty for Varus Osteoarthritis

BACKGROUND

In patients with end-stage varus ankle osteoarthritis (OA), hindfoot varus malalignment resulting from the varus deformity of the ankle joint is common. Although total ankle arthroplasty (TAA) performed to correct varus deformity of the ankle joint has the effect of correcting hindfoot alignment, no reports to date have described how much hindfoot alignment correction can be achieved. The purpose of this study was to identify correlation between ankle deformity correction and hindfoot alignment change after performing TAA in patients with end-stage varus ankle OA.

METHODS

A total of 61 cases that underwent TAA for end-stage varus ankle OA and followed up for at least 1 year were enrolled for this study. Correlation between changes of tibial-ankle surface angle (TAS), talar tilt (TT), and tibiotalar surface angle (TTS) and changes of hindfoot alignment angle (HA), hindfoot alignment ratio (HR), and hindfoot alignment distance (HD) measured preoperatively and at postoperative year 1 was analyzed.

RESULTS

TAS, TT, and TTS changed from 83.9 ± 4.1 degrees, 5.8 ± 5.0 degrees, and 78.1 ± 5.9 degrees, respectively, before operation to 89.2 ± 2.1 degrees, 0.4 ± 0.5 degrees, and 88.7 ± 2.3 degrees, respectively, after operation. HA, HR, and HD also changed from -9.2 ± 4.6 degrees, 0.66 ± 0.18, and -11.2 ± 6.9 mm to -3.7 ± 4.1 degrees, 0.48 ± 0.14, and -5.0 ± 5.3 mm. All the changes were statistically significant (P < .001, respectively). The regression slope of correlation was 0.390 (R² = 0.654) between TTS and HA; 0.017 (R² = 0.617) between TTS and HR; and 0.560 (R² = 0.703) between TTS and HD.

CONCLUSION

In patients with end-stage varus ankle OA, changes of hindfoot alignment could be predicted based on degree of ankle deformity corrected with TAA.

LEVEL OF EVIDENCE

Level IV, case series.

Alignment of the hindfoot in total knee arthroplasty: a systematic review of clinical and radiological outcomes

AIMS

Patients with a deformity of the hindfoot present a particular challenge when performing total knee arthroplasty (TKA). The literature contains little information about the relationship between TKA and hindfoot alignment. This systematic review aimed to determine from both clinical and radiological studies whether TKA would alter a preoperative hindfoot deformity and whether the outcome of TKA is affected by the presence of a postoperative hindfoot deformity.

METHODS

A systematic literature search was performed in the databases PubMed, EMBASE, Cochrane Library, and Web of Science. Search terms consisted of "total knee arthroplasty/replacement" combined with "hindfoot/ankle alignment". Inclusion criteria were all English language studies analyzing the association between TKA and the alignment of the hindfoot, including the clinical or radiological outcomes. Exclusion criteria consisted of TKA performed with a concomitant extra-articular osteotomy and case reports or expert opinions. An assessment of quality was conducted using the modified Methodological Index for Non-Randomized Studies (MINORS). The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and registered in the PROSPERO database (CRD42019106980).

RESULTS

A total of 17 studies were found to be eligible for review. They included six prospective and ten retrospective studies, and one case-control study. The effects of TKA showed a clinical improvement in the hindfoot deformity in three studies, but did not if there was osteoarthritis (OA) of the ankle (one study) or a persistent deformity of the knee (one study). The radiological alignment of the hindfoot corrected in 11 studies, but did not in the presence of a rigid hindfoot varus deformity (in two studies). The effects of a hindfoot deformity on TKA included a clinical association with instability of the knee in one study, and a shift in the radiological weightbearing axis in two studies. The mean MINORS score was 9.4 out of 16 (7 to 12).

CONCLUSION

TKA improves both the function and alignment of the hindfoot in patients with a preoperative deformity of the hindfoot. This may not apply if there is a persistent deformity of the knee, a rigid hindfoot varus deformity, or OA of the ankle. Moreover, a persistent deformity of the hindfoot may adversely affect the stability and longevity of a TKA. These findings should be interpreted with caution due to the moderate methodological quality of the studies which were included. Therefore, further prospective studies are needed in order to determine at which stage correction of a hindfoot deformity is required to optimize the outcome of a TKA. Cite this article: Bone Joint J 2021;103-B(1):87-97.

Correction of excessive intraarticular varus deformities in total knee arthroplasty is associated with deteriorated postoperative ankle function

PURPOSE

The aim of this study was to demonstrate, whether the degree of limb alignment correction in varus knee osteoarthritis correlated with an increase in ankle symptoms and to define a cut-off value concerning the degree of correction above which to expect ankle problems.

METHODS

Ninety-nine consecutive patients with preoperative intraarticular varus knee deformities who underwent total knee arthroplasty were retrospectively analyzed. Patients were examined clinically (Knee Society Score, Forgotten Joint Score, Foot Function Index, Range of Motion of the knee and ankle joint, pain scales) as well as radiologically. The mean follow-up time was 57 months.

RESULTS

The degree of operative limb alignment correction strongly correlated with the Foot Function Index (R = 0.91, p < 0.05). Given this, higher degrees of knee malalignment corrections were associated with worse postoperative outcomes in the knee and ankle joint-despite postoperative improved joint line orientations. Subsequently, a cut-off value for arthritic varus deformities (14.5°) could be calculated, above which the prevalence of ankle symptoms increased manifold [OR = 15.6 (3.2-77.2 95% CI p < 0.05)]. Furthermore, ROM restrictions in the subtalar joint were associated with a worse outcome in the ankle joint.

CONCLUSIONS

When correcting excessive intraarticular varus knee osteoarthritis, surgeons have to be aware of possible postoperative ankle symptoms and should consider ankle deformities or decreased subtalar ROM before operative procedures.

LEVEL OF EVIDENCE

III.

Amelioration in Ankle Pain and Improvement in Function After Total Knee Arthroplasty for Ipsilateral Knee and Ankle Osteoarthritis: A Report of Two Cases

We report 2 cases of ipsilateral ankle and knee osteoarthritis (OA), with the chief complaint being chronic ankle and knee pain. In the first patient, the ankle pain was more severe than the knee pain, whereas the second patient had more severe pain in the knee than in the ankle. In both cases, varus malalignment of the knee and varus tilt of the ankle joint were detected on standing radiographs. The severity of OA was found to be grade 4 in the knee, according to the Kellgren–Lawrence grading system, and stage IIIa in the ankle, according to the modified Takakura ankle OA classification system. Navigation-assisted total knee arthroplasty was performed in both cases, leading to a decreased degree of varus malalignment in the knee and ankle, as well as a significantly improved patient-based outcome in both joints. Correction of malalignment of the ankle by total knee arthroplasty relieved the severe pain and restored optimal function in the ankle without surgical intervention.

Aggravation of Ankle Varus Incongruency Following Total Knee Replacement Correcting ≥10° of Genu Varum Deformity: A Radiographic Assessment

BACKGROUND

This study aimed to investigate the change in ankle varus incongruencies following total knee replacement (TKR) in patients with preoperative genu varum deformity of ≥10°.

METHODS

The study cohort was composed of patients who underwent TKR in a single institution for knee osteoarthritis with preoperative genu varum deformity of ≥10° and concomitant varus ankle incongruencies. Eight radiographic measurements were evaluated preoperatively and postoperatively: mechanical tibiofemoral angle, mechanical lateral distal femoral angle, medial proximal tibial angle, lateral distal tibial angle, tibial plafond inclination, talar inclination, tibiotalar tilt angle (TTTA), and tibia-mechanical axis angle. Of these, TTTA represented the quantitative degree of ankle joint incongruency.

RESULTS

A total of 110 patients (male = 2; female = 108) were included in the analysis. The mean patient age was 68.9 (standard deviation [SD] 7.2) years at the time of TKR. All radiographic measurements showed significant changes postoperatively, representing the appropriate correction of genu varum deformity and restoration of the mechanical axis. Nineteen patients (17.3%) showed postoperative decrease in TTTA, 2 (1.8%) remained the same, and 89 (80.9%) showed increase. Overall, mean preoperative and postoperative TTTA were 3.3° (SD 2.2°) and 4.7° (SD 2.9°), respectively (P < .001), representing the aggravation of varus ankle incongruencies.

CONCLUSION

Varus ankle incongruencies showed aggravation following TKR despite correction of genu varum deformity and restoration of the mechanical axis. This could be an important cause of postoperative increase or development of ankle pain following TKR. Therefore, patients with preoperative varus ankle incongruencies need to be warned of possible aggravation of ankle symptoms and be evaluated before TKR.

LEVEL OF EVIDENCE

Prognostic level III.

The effect of varus knee deformities on the ankle alignment in patients with knee osteoarthritis

Background

We evaluated the compensatory change in ankle alignment due to knee malalignment and its relationship with varus knee deformities, as well as sex differences in compensation.

Methods

From October 2016 to September 2017, 103 patients with end-stage knee osteoarthritis underwent primary total knee arthroplasty (TKA). Ninety-five knees (78 patients) were included. The hip-knee-ankle angle (HKA) and ankle alignment and tilt were evaluated with full-leg standing anteroposterior radiographs. The ankle alignment was estimated according to the tibiotalar angle, tibial anterior surface angle (TAS), and lateral distal tibial angle. The talar tilt angle (TT), anatomical talocrural angle, angle between the tibial plateau and distal tibial plafond, angles between the ground and distal tibial plafond, and angles between the ground and upper talus were measured to evaluate ankle tilt. The patients were separated into two sex-based groups; correlations between the HKA and ankle parameters were estimated.

Results

The mean HKA in men and women was 8.16 ± 4.36° and 7.69 ± 5.93°, respectively. The relative tilt of the talus and distal tibia plafond to the ground was increased when varus knee deformities progressed. In women, there was a positive correlation between the knee alignment and TAS (r = − 0.295, p = 0.016). As the knee mechanical axis became more varus, the distal tibia plafond became more valgus. In women, a negative correlation was observed between the HKA and TT (r = − 0.359, p = 0.003). Compensatory changes in the ankle alignment and TT to knee alignment were not observed in men.

Conclusion

Compensatory ankle changes should be considered before TKA.

Preoperative tibial mechanical axis orientation and articular surface design influence on the coronal joint line orientation relative to the ground during gait after total knee arthroplasties

PURPOSE

Neutral lower limb alignment does not necessarily produce a horizontal joint line after total knee arthroplasty (TKA). The orientation of the pre- and postoperative tibial mechanical axes (TMAs-G), tibial component, and joint line relative to the ground were evaluated.

METHODS

The study group included 46 knees, 23 posterior-stabilized (PS) and 23 bicruciate-stabilized (BCS) TKAs. Using whole-leg standing radiographs, the static orientation of the pre- and postoperative TMAs-G and the tibial component as well as the postoperative alignment were measured. Applying image-matching techniques, the dynamic coronal orientation of the tibial component and joint line over the stance phase of gait were analysed. The correlation between static and dynamic orientation of the tibial component and differences in the joint line between the PS and BCS TKAs were evaluated.

RESULTS

In standing, the postoperative TMA-G (0.8° ± 2.8°) and tibial component (1.5° ± 2.4°) were laterally tilted with a strong correlation. The preoperative lateral tilt of the TMA-G (7.9° ± 5.1°) was a significant predictor of the postoperative TMA-G. The lateral tilt of the tibial component increased to 5.1° ± 2.4° on dynamic analysis, and was moderately correlated to static orientation. The dynamic orientation of the joint line was smaller for the BCS (1.8° ± 2.4°) compared to the PS (5.5° ± 2.7°) TKA.

CONCLUSION

Even with a mechanically well-aligned TKA, a lateral tilt of the tibial component was identified due to the lateral tilt of the postoperative TMA-G and the stance phase of gait. The BCS can better accommodate the residual lateral tilt of the joint line due to the 3° medial inclination of the joint surfaces of the implant. This study increases the awareness of surgeons regarding the possibility of the coronal joint line orientation to influence preoperative TMA-G and be accommodated by articular surface design, even in mechanically aligned TKA.

LEVEL OF EVIDENCE

IV.

Following the correction of varus deformity of the knee through total knee arthroplasty, significant compensatory changes occur not only at the ankle and subtalar joint, but also at the foot

PURPOSE

This study aimed to assess radiological changes of the ankle joint, subtalar joint and foot following the correction of varus deformity of the knee with total knee arthroplasty (TKA). It was hypothesized that following the correction of varus deformity by TKA, compensatory reactions would occur at the subtalar joint in accordance with the extent of the correction.

METHODS

For this prospective study, 375 knees of patients who underwent TKA between 2011 and 2012 were enrolled. The varus angle of the knee, talar tilt of the ankle joint (TT), ground-talar dome angle of the foot (GD), anterior surface angle of the distal tibia and lateral surface angle of the distal tibia, heel alignment ratio (HR), heel alignment angle (HA), and heel alignment distance (HD) were measured on radiographs obtained pre-operatively and at post-operative 6 months.

RESULTS

The mean correction angle in varus deformity of the knee was 10.8 ± 4.1°. TT and GD changed significantly from 0.4 ± 1.9° and 6.5 ± 3.1° pre-operatively to 0.1 ± 1.8° and 0.2 ± 2.1°, respectively (p = 0.007, p < 0.001). No correlation was found between the preop-postop variance in mechanical axis of the lower extremity (MA) and TT, but there was a strong correlation between the preop-postop variance in MA and GD (r = 0.701). HR, HA and HD also changed significantly post-operatively, and the preop-postop variance in MA showed correlations with the preop-postop variances in HR, HA and HD (r = 0.206, - 0.348, and - 0.418). TT and the three indicators of hindfoot alignment all shifted to varus whereas GD was oriented in valgus.

CONCLUSION

Following the correction of varus deformity of the knee through TKA, significant compensatory changes occurred not only at the ankle and subtalar joints, but also at the foot. The findings of this study are useful in predicting the orientation of changes in the ankle and subtalar joints and the foot following TKA, and in determining the sequence of surgery when both the ankle and knee have a problem. In other words, changes in the parts of the lower extremity below the ankle joint following the correction of varus deformity of the knee must be considered when TKA is planned and performed. Patients who have problems at the ankle, subtalar, and foot joints in addition to varus deformity of the knee are recommended to undergo knee joint correction first.

LEVEL OF EVIDENCE

II.

Changes in Hip, Knee, and Ankle Coronal Alignments After Total Hip Arthroplasty With Transverse Femoral Shortening Osteotomy for Unilateral Crowe Type IV Developmental Dysplasia of the Hip

BACKGROUND

To investigate changes in lower extremity coronal alignment in patients with unilateral Crowe type IV developmental dysplasia of the hip who underwent total hip arthroplasty with transverse femoral shortening osteotomy.

METHODS

We reviewed the preoperative and 1-year postoperative full-length lower extremity radiographs of 25 patients. Femoral offset (FO), mechanical hip-knee-ankle angle, anatomical axis, mechanical axis deviation (MAD), mechanical lateral proximal femoral angle, anatomical medial proximal femoral angle, mechanical lateral distal femoral angle, anatomical lateral distal femoral angle, knee joint line congruency angle, mechanical medial proximal tibial angle, mechanical lateral distal tibial angle, ankle joint line orientation angle, tibial plafond talus angle, extremity length, and pelvic obliquity were measured on both the operative and nonoperative sides.

RESULTS

Postoperatively, there were significant changes in FO (P = .001), hip-knee-ankle angle (P = .004), MAD (P = .016), mechanical lateral proximal femoral angle (P = .001), anatomical medial proximal femoral angle (P = .012), mechanical lateral distal femoral angle (P = .043), and ankle joint line orientation angle (P = .012) on the operative side. Only MAD (P = .035) changed significantly on the nonoperative side.

CONCLUSION

Modification of FO and reconstruction of hip joint anatomy led to neutralization of knee and ankle valgus alignment. Effects on the nonoperative side were minimal.

Clinical usefulness of hindfoot assessment for total knee arthroplasty: persistent post-operative hindfoot pain and alignment in pre-existing severe knee deformity

PURPOSE

The purpose of this study was to compare the hindfoot alignment and symptoms in patients with pre-existing moderate and severe knee deformities after total knee arthroplasty (TKA).

METHODS

Eighty knees of 75 patients who underwent TKA for varus osteoarthritis were enrolled retrospectively and evaluated the following pre-operatively and at 2 years post-operatively: the American Orthopaedic Foot and Ankle Society ankle-hindfoot scale (pain and function scores), calcaneal pitch, and naviculocuboid overlap as an indicator of hindfoot alignment. The knees were divided into two groups according to the pre-operative hip-knee-ankle angle defined as the angle between the mechanical axis of the femur and the tibia: group M with genu varus of ≤6°, and group S with varus >6°.

RESULTS

The pain (p = 0.03) and function (p = 0.02) scores improved in group M; however, in group S, these measures did not change. The differences between the groups were not significant concerning the pre-operative calcaneal pitch and naviculocuboid overlap. The post-operative pitch (p = 0.03) and the overlap (p = 0.04) in group M was significantly greater and less than those in group S, respectively. Although the pitch (p < 0.01) and the overlap (p = 0.03) increased in group M, these did not change in group S. Post-operative hindfoot pain and valgus remained in patients in group S.

CONCLUSIONS

For pre-existing moderate knee deformities, a relationship was observed between post-operative knee alignment and compensatory hindfoot alignment, whereas patients with severe deformities experienced persistent post-operative hindfoot pain and valgus alignment. It was concluded that evaluations and managements of residual symptoms after TKA including the hindfoot are important. These findings are clinically relevant that perioperative evaluation of the hindfoot should be required in knee surgery. To help improve the outcomes of TKA, clinicians may consider perioperative intervention in the insole and/or physical therapy of the foot and ankle.

LEVEL OF EVIDENCE

Therapeutic study, Level III.