No Radiographic Evidence of Medial Collateral Ligament Elongation in Valgus Osteoarthritic Knees Enables Treatment with Kinematically Aligned Total Knee Arthroplasty

Abstract

When performing caliper-verified kinematically aligned total knee arthroplasty (KA TKA) in the osteoarthritic (OA) knee with valgus deformity, an elongated medial collateral ligament (MCL) could result in a valgus setting of the tibial component. The present study analyzed KA TKA in patients with valgus deformities (i.e., tibiofemoral angle > 10 degrees of valgus) and determined (1) the occurrence of radiographic MCL elongation, (2) the incidence of lateral collateral ligament (LCL) and posterior cruciate ligament (PCL) release and the use of constrained components, and (3) whether the 1-year Forgotten Joint Score (FJS), Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR), and Likert satisfaction score were comparable to KA TKAs for OA deformities ≤10 degrees of valgus. One hundred and two consecutive patients who underwent KA TKA by a single surgeon were analyzed radiographically and clinically at a minimum follow-up of 1 year. Radiographic MCL elongation was identified by a greater than 1 degree of valgus orientation of the tibial component relative to the OA tibial joint line. Twenty-six patients had a radiographic anatomic tibiofemoral angle greater than 10 degrees of valgus (range of OA deformity: 11–23 degrees of valgus). Seventy-six had an OA deformity ≤10 degrees of valgus (10-degree valgus to –14-degree varus). No patient had MCL elongation or a ligament release, or required constrained components. The median FJS of 78, OKS of 42, and KOOS JR of 76, and the 85% satisfaction rate of the patients with greater than 10 degrees of OA valgus deformity were not significantly different from those with ≤10 degrees of OA valgus deformity (p ≥ 0.17). Because MCL elongation was not detected in OA deformities up to 23 degrees of valgus, the risk of under-correcting the valgus deformity leading to instability and poor outcome scores is low when performing KA TKA using primary components without releasing the LCL and/or PCL.

Level of Evidence: IV.

 

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Keywords

knee replacement - kinematic alignment - valgus deformity - patient-reported outcomes

Surgeons who perform total knee arthroplasty (TKA) in osteoarthritic (OA) knees with valgus deformities (i.e., anatomic tibiofemoral angle [aTFA] on a standing radiograph >10 degrees) might be concerned about the medial collateral ligament (MCL) being elongated and the knee being unstable.[1] [2] [3] [4] [5] [6] To reduce the risk of instability and achieve mechanical alignment (MA) of the limb and a neutral joint line obliquity, the surgeon might apply corrective measures that consist of using constrained components and releasing a tight lateral collateral ligament (LCL) and posterior cruciate ligament (PCL).[6] [7] [8]

Kinematically aligned total knee arthroplasty (KA TKA) resurfaces the patient's prearthritic knee to restore the articular surfaces, limb alignment, and joint line obliquity. Using primary components that restore the articular surface geometry and soft-tissue constraints of the native knee, these steps align the knee's three kinematic axes with the axes of the femoral and tibial components.[9] [10] Resurfacing the prearthritic knee retains the native resting lengths of the collateral ligaments and PCL, eliminating the need for their release.[11]

For two reasons, surgeons can be reluctant to use kinematic alignment (KA) when treating valgus deformities with an aTFA greater than 10 degrees.[4] One is that an elongated MCL would change the native rectangular extension space into one that is trapezoidal and abnormal. The surgeon would have to cut the tibia in valgus relative to the prearthritic joint line to convert the trapezoid into a stable rectangular extension space.[12] Hence, measurements of the anatomic tibial joint line angle (aTJLA) on a standing anteroposterior (AP) radiograph that show a tibial component set in more valgus than the OA knee could detect the occurrence of MCL elongation ([Fig. 1]). Another reason is that the effectiveness of correcting the posterolateral capsular contracture by manipulating the knee with trial components into full extension without releasing the LCL and PCL has yet to be determined.

Fig. 1 The composite shows a two-dimensional (2D) model of a tibial component superimposed on standing anteroposterior (AP) radiographs to analyze the effect of performing kinematically aligned (KA) total knee arthroplasty (TKA) on an osteoarthritic (OA) knee with an (A) intact medial collateral ligament (MCL; yellow arc) and (B) MCL elongation (magenta curved line). Lines representing the anatomic femoral (blue) and tibial (orange) axes connect the centers of transverse lines (cyan lines), drawn 5 and 12 cm proximal and distal to the joint line, respectively. The anatomic tibiofemoral angle (aTFA) is the intersection of the anatomic axes (+ valgus). The anatomic tibial joint line angle (aTJLA) is the intersection of the tibial joint line and the tibial anatomic axis (valgus is ≥90 degrees). In (A), the MCL is intact because the tibial component is not greater than 1 degree of valgus than the OA knee (i.e., both 89 degrees). In (B), the MCL is elongated because the tibial component is 3 degrees more valgus than the OA knee, which under-corrected the knee deformity by 3 degrees.

Accordingly, the present study analyzed KA TKA in OA deformities ranging from an aTFA of 23 degrees of valgus to 14 degrees of varus, divided them into two cohorts (>10 and ≤10 degrees of valgus deformities), and determined for patients with a greater than 10 degrees of valgus deformity (1) the occurrence of MCL elongation by determining whether the tibial component was more valgus than the OA tibial joint line (i.e., >1 degrees), (2) the incidence of LCL and PCL release and use of constrained components, and (3) whether the 1-year Forgotten Joint Score (FJS), Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR), and Likert satisfaction score were comparable to patients with ≤10 degrees of valgus deformities.

Methods

The study was approved by the local institutional review board (Pro00073548). The surgeon (A.J.N.), who had just graduated from an accredited 1-year knee arthroplasty fellowship, analyzed the first 112 patients who had OA of the knee that fulfilled the Medicare guidelines for treatment with a primary TKA from November 2019 to October 2021. The surgeon included all patients regardless of varus–valgus (V-V) deformity and flexion contracture severity and treated each with KA. Patients undergoing TKA with a history of prior intra-articular fracture, septic arthritis or inflammatory arthritis, and who could not be followed up 1 year after their KA TKA were excluded.

The surgeon used a previously described technique to perform KA TKA with PCL retention and manual instruments using a cemented constant radius femoral component, an asymmetric tibial baseplate mated with an insert featuring ball-in-socket medial conformity, flat lateral articulation, and patella resurfacing (GMK Sphere, Medacta International, Castel San Pietro, Switzerland, www.medacta.com, accessed on November 5, 2023).[13] The surgical steps and verification checks were the same for all deformities except for the fixed valgus knee deformity with a flexion contracture. The posterolateral capsule is contracted in these knees, which the surgeon can detect by knee examination before incision so that later in the procedure, the capsule is stretched by manipulating the knee into extension with trial components.

The following are the salient surgical steps of KA. The surgeon relies on four caliper measurements of the femoral resections to verify that the femoral component resurfaces the patient's prearthritic articular surface. When necessary, each femoral resection is corrected so that its thickness equals that of the condyle of the femoral component after compensating 2 mm for cartilage loss and 1 mm for the kerf made by the saw blade to limit deviations from the prearthritic distal and posterior femoral articular surfaces to within 0 ± 0.5 mm.[14] The surgeon makes four caliper measurements to verify that the tibial resection sets the tibial component's V-V orientation and posterior slope such that the patient's prearthritic tibial articular surface is resurfaced. When necessary, differences between the medial and lateral thicknesses of the tibial resection are fine-tuned by recutting the tibia to correct the difference. Equalization of these two thicknesses is the initial verification that the V-V orientation of the tibial resection is correct. When necessary, differences between the medial anterior and posterior thicknesses are fine-tuned by recutting the tibia to correct the difference, which sets the posterior slope.[15]

A second verification of the tibial resection's V-V orientation occurs when the surgeon manually assesses the knee balance in extension after inserting the tightest fitting spacer block. The surgeon applies a V-V moment to the knee and looks for liftoff of the medial and lateral femoral and tibial resection from the spacer block. In all knees, except those with a posterolateral capsular contracture indicating a fixed valgus deformity, the tibial resection is fine-tuned by removing additional tibia until the extension space becomes rectangular.[16]

In those with a fixed valgus deformity, the surgeon anticipates that the tight posterolateral capsule will cause asymmetry in the extension space, identified by medial liftoff between the femur or tibial resection and the spacer block. When a medial liftoff occurs, the surgeon corrects it not by fine-tuning the tibial resection but rather by exchanging the spacer block for trial components and manipulating the knee into full extension. This step stretches the posterolateral capsular contracture and corrects the extension loss.

The surgeon selects the optimal thickness for the insert by observing changes in the external orientation of the tibia in extension and internal tibial orientation in 90-degree flexion as measured by an insert goniometer. For each insert thickness, the surgeon records the extension and flexion tibial orientations measured at the intersection of a line marking a degree along the course of a radial dial etched into the anteromedial surface of a trial insert and a longitudinal laser mark on the medial femoral condyle. The optimal thickness is the insert that provides the greatest orientation in extension and/or 90-degree flexion.[17] The surgeon refrains from releasing collateral ligaments and the PCL. Hence, when a KA TKA appears too tight, the surgeon readjusts the components so their position and orientation resurface the knee's prearthritic articulation.

Each patient had preoperative and postoperative AP standing knee radiographs obtained according to the recommendation of the Knee Society.[18] [19] The Kellgren–Lawrence grade determined the severity of OA.[20] One author (A.S.D.) measured the anatomic tibiofemoral knee angle (aTFA; +valgus/–varus) and aTJLA (valgus >90 degrees) with image analysis software (Horos 4.0.1, horosproject.com, last accessed on January 26, 24) using a previously described technique with good to excellent repeatability and reproducibility.[4] [19] [21] [22] The preoperative aTFA assigned patients to one cohort with an OA deformity greater than 10 degrees of valgus and another with an OA deformity ≤10 degrees of valgus.[4] A tibial component with an aTJLA greater than 1 degree of valgus than the OA aTJLA indicated MCL elongation ([Fig. 1]). A review of the operative report identified the occurrence of LCL and PCL release and implant constraint.

At a minimum follow-up of 1 year, patients completed an emailed electronic patient-reported outcome measures (PROMs) assessment consisting of the FJS (100: best; 0: worst), OKS (48: best; 0: worst), KOOS JR (100: best; 0: worst), and 5-point Likert satisfaction score (very satisfied, satisfied, neutral, dissatisfied, and very dissatisfied), and were asked to provide information about any reoperation.

Data Analyses

An a priori sample size calculation was conducted based on the 14-point minimum clinically important difference (MCID) of the FJS.[23] The effect size was 0.7.[24] With a significance criterion of α = 0.05, power = 0.80, and an allocation ratio of 0.3, the minimum sample size needed was 22 patients with an OA deformity greater than 10 degrees of valgus and 72 patients with an OA deformity ≤10 degrees of valgus.

The Shapiro–Wilk test determined the normality of the dependent variables. Mean ± standard deviation (SD), median, and interquartile range (IQR) described the dependent variables with normal and non-normal distributions. Fisher's exact test, two-sample t-test, and Wilcoxon rank-sum test determined the significance of differences in patient characteristics of sex, Kellgren–Lawrence grade, age, body mass index (BMI), knee extension, knee flexion, radiographic measures, 1-year PROMs, and satisfaction rate between patients with a >10 and ≤10 degrees of OA valgus deformity. Statistical software (JMP 17.1 for Mac, http://www.jmp.com) was used for all analyses. A p-value less than 0.05 indicated a statistically significant difference.

 

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Results

Of the 112 consecutive patients treated with KA TKA, 102 (91%) completed the PROMs at a minimum follow-up of 1 year. Twenty-six patients had an OA deformity greater than 10 degrees of valgus (range: 11–23 degrees). Of those, 85% had Kellgren–Lawrence grade IV OA severity. Seventy-six patients had an OA deformity ≤10 degrees of valgus (range: 10 degrees of valgus to 14 degrees of varus). Of those, 68% had a Kellgren–Lawrence grade IV OA severity. Patient demographics and preoperative characteristics were not significantly different between cohorts (p ≥ 0.13; [Table 1]).

Table 1 Patient demographics and preoperative characteristics were comparable between patients with an osteoarthritic (OA) deformity >10 and ≤10 degrees of valgus

	OA deformity
	> 10 degrees of valgus	≤10 degrees of valgus	p-value
Number of patients (N)	26	76
Patients' preoperative characteristics and function scores
Number of patients ( N )
Women/men	18/8	45/31	0.30[a]
Kellgren–Lawrence grade I/II/III/IV	0/0/4/22	0/0/24/52	0.13[a]
Mean ± standard deviation (SD)
Age (y)	67 ± 11	68 ± 10	0.79[b]
BMI[c] (kg/m2)	32 ± 6	32 ± 6	0.84[b]
Knee extension (degrees)	2 ± 3	3 ± 6	0.65[b]
Knee flexion (degrees)	111 ± 10	107 ± 12	0.37[b]
Oxford Knee Score (48: best; 0: worst)	16 ± 7	18 ± 9	0.44[b]
KOOS JR[d] (100: best; 0: worst)	38 ± 15	41 ± 18	0.84[b]
Mean ± SD (range) preoperative coronal alignment (degrees; – varus; + valgus)
Anatomic tibiofemoral angle	14 ± 3.7 (11–23)	–1 ± 4.6 (–14 to 10)	< 0.01[b]
Anatomic tibial joint line angle	89 ± 1.8 (83–92)	85 ± 2.5 (77–90)	< 0.01[b]

^a Fisher's exact test.

^b Two-sample t-test.

^c Body mass index.

^d Knee Injury and Osteoarthritis Outcome Score for Joint Replacement.

No patient had radiographically detectable MCL elongation, as all the kinematically aligned tibial components were positioned less than 1 degrees of valgus relative to the OA tibial joint line ([Fig. 2] ). No patient required an LCL or PCL release. All the patients were treated with primary components.

Fig. 2 The composite illustrates the measurement of the anatomic tibial joint line angle (aTLJA) in the osteoarthritic (OA) knee with valgus deformity (left) and after kinematically aligned (KA) total knee arthroplasty (TKA; middle). The bar chart (right) shows the number of patients with a different aTJLA, computed as the tibial component minus the OA knee. A positive value indicates that the tibial component is valgus relative to the OA tibial joint line. AP, anteroposterior.

The median postoperative FJS, OKS, and KOOS JR of 79, 42, and 76 points, respectively, in KA TKA patients who had an OA deformity greater than 10 degrees of valgus were not statistically different from the median values of 81, 43, and 80 points of those who had an OA deformity ≤10 degrees of valgus (p ≥ 0.17). The proportion of satisfied or very satisfied patients was 88% for those with an OA deformity greater than 10 degrees of valgus and was not significantly different from the 93% for those with an OA deformity ≤10 degrees of valgus (p = 0.27; [Table 2]).

Table 2 Comparison of postoperative patient-reported outcome measures (PROMs), satisfaction rate, and coronal alignment between patients with an osteoarthritic (OA) deformity >10 and ≤10 degrees of valgus

	OA deformity
	> 10 degrees of valgus	≤10 degrees of valgus	p-value
Months to follow up (mean ± SD[a])	20 ± 4	21 ± 5	0.25[b]
Median and (IQR)[c] of postoperative PROMs
Forgotten Joint Score (100: best; 0: worst)	79 (47–96)	81 (58–98)	0.17[d]
Oxford Knee Score (48: best; 0: worst)	42 (34–45)	43 (38–46)	0.55[d]
KOOS JR[e] (100: best; 0: worst)	76 (59–100)	80 (70–98)	0.52[d]
Likert Satisfaction Scale (very satisfied/satisfied/neutral/dissatisfied/very dissatisfied), %	58/30/12/0/0	67/26/6/1/0	0.27[f]
Mean ± SD (range) postoperative coronal alignment (degrees; – varus; + valgus)
Anatomic tibiofemoral angle	7 ± 3.6 (2–15)	3 ± 3.9 (–12 to 9)	< 0.01[b]
Anatomic tibial joint line angle	87 ± 1.9 (83–91)	86 ± 2.2 (81–90)	< 0.01[b]

^a Standard deviation.

^b Two-sample t-test.

^c Interquartile range.

^d Wilcoxon rank-sum test.

^e Knee Injury and Osteoarthritis Outcome Score for Joint Replacement.

^f Fisher's exact test.

No patient with an OA deformity greater than 10 degrees of valgus had a reoperation. One patient with an OA deformity ≤10 degrees of valgus had an acute periprosthetic joint infection treated with irrigation, debridement, and component retention.

 

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Discussion

The three most important findings of this study analyzing KA TKA were that (1) there was no radiographic evidence of MCL elongation in patients who had an OA valgus deformity ranging from 11 to 23 degrees, (2) none of these patients required an LCL or PCL release or a constrained implant, and (3) the median FJS, OKS, KOOS JR, and Likert patient-reported outcome results were comparable to patients who had an OA deformity ≤10 degrees of valgus.

Despite the common assumption that the MCL elongates in valgus deformities, the radiographic assessment after KA TKA did not confirm it. There are two theoretical scenarios for MCL elongation: traumatic and subfailure loading. First, the traumatic mechanism is unlikely because the reported yield of the MCL is 500 to 600 N. The MCL must stretch 7 to 8 mm before it yields, which would require a traumatic event rarely reported by a patient with fixed valgus deformities and would make the knee so unstable that it would not support the patient during weightbearing.[25] [26] [27] Second, it is unlikely that subfailure cyclical loading elongates the MCL because in vivo animal and human cadaveric models show an increase in collateral ligament stiffness without attenuation.[28] [29] Hence, the clinical appearance of a wide medial joint space on preoperative standing radiographs does not indicate MCL elongation, as slight flexion in patients with a valgus deformity and a preoperative flexion contracture slackens the MCL, which the clinician might misinterpret as MCL elongation[30] ([Fig. 3]).

Fig. 3 The composite shows (A) a patient standing with a fixed right valgus deformity, (B) the preoperative standing knee radiograph, and (C) a postoperative radiograph showing a 12-degree correction after kinematically aligned (KA) total knee arthroplasty (TKA) to 11 degrees, which matches the contralateral knee. The widened medial joint space does not indicate medial collateral ligament (MCL) elongation, which occurs because the MCL is slack from the knee's flexion contracture. AP, anteroposterior.

Regarding implant constraint, KA treated the valgus deformity with primary components and PCL retention, founded on the anatomical fact that the lateral femoral condyle is not hypoplastic in the non-OA and OA valgus knees.[31] [32] [33] KA enabled the correction of the OA valgus deformity up to 23 degrees without releasing the LCL and PCL, which differs from the management recommended for MA.[3] [4] [5] One reason for the difference is that KA restores the pre-arthritic knee and limb alignment instead of changing the patient's prearthritic alignment to a hip–knee–ankle angle of 0 ± 3 degrees, which can slacken the MCL and may require the release of the LCL and PCL, thus destabilizing the knee.[3] [4] Another reason is that MA changes the joint line obliquity, whereas KA does not.[34] Since most valgus knees have an apex distal joint line obliquity, the MA surgeon must under-resect the lateral femoral condyle to neutralize the joint obliquity and release presumably tight lateral soft tissues.[35] Because KA avoids alterations to patients' prearthritic hip–knee–ankle angle and their joint line obliquity and thus reduces iatrogenic knee instability, the surgeon can expect to utilize primary implants when treating valgus deformities.

Regarding postoperative function and satisfaction, KA TKA resulted in comparable FJS, OKS, KOOS JR, and Likert satisfaction score in patients with deformities ranging from –14 degrees of varus to 23 degrees of valgus. The median FJS, OKS, and Likert satisfaction score in patients with an OA deformity greater than 10 degrees of valgus are comparable to patients undergoing medial unicompartmental knee arthroplasty and previous reports of KA TKA.[16] [36] [37] Two reasons can explain why KA for patients who have an OA deformity greater than 10 degrees of valgus resulted in high function and satisfaction. One reason is that KA TKA closely restores the forces in the medial and lateral compartments to native levels irrespective of preoperative deformity.[38] [39] Another reason is that changing the patient's presurgical functional limb and femoral phenotype by more than one category and changing the medial articular surface by more than 1 mm lowers the PROMs more than the MCID, which KA TKA avoids.[40] [41] [42]

The present study had the following limitations. First, the maximum valgus deformity included in the study was 23 degrees. Hence, the conclusions from the study cannot be applied to valgus deformities exceeding 23 degrees. Second, one surgeon generated the study results using one component design. However, the surgeon was a novice at performing KA TKA at the initiation of the study, and thus, surgeons considering KA TKA for valgus OA could be encouraged that a lack of experience is not a contraindication for performing KA TKA, including more severe valgus deformities. Third, the medial ball-in-socket insert design with PCL retention might have prevented anterior knee pain and patellofemoral instability, which can occur when KA TKA treats valgus knee OA.[40] A medial ball-in-socket insert design in conjunction with PCL retention promotes soft-tissue-driven internal tibial rotation during knee flexion, which dynamically medializes the tibial tubercle during flexion and thus maintains patella engagement in the trochlea groove.[43] Accordingly, the study's findings might not apply to other component designs. Fourth, the study did not include measurements from long-leg radiographs. The study's pre- and postoperative radiographic measurements reflect the Knee Society's recommendations and make them comparable to contemporary publications regarding the treatment of valgus OA deformities.[3] [4] [21] The last limitation is the mean follow-up time of 20 months. Hence, this study did not provide long-term outcomes. Because the purposes of the study were to radiographically detect MCL elongation in valgus OA knees, the incidence of ligament releases, the use of constrained components, and compare PROMs after KA TKA between patients who had an OA deformity >10 and ≤10 degrees of valgus, a longer follow-up time would not change the study's conclusions.[44]

 

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Conclusions

Based on the results showing a lack of radiographic evidence of MCL elongation in OA knees with valgus deformities up to 23 degrees and excellent postoperative functional outcomes, KA TKA is an effective treatment for these patients. Surgeons performing KA TKA for patients with valgus deformities can expect to retain the LCL and PCL and use primary components.

 

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Conflict of Interest

None declared.

Ethical Approval

This study was approved by the Institutional Review Board.

Authors Contributions

All the authors have made substantial contributions to all of the following: (1) the conception and design of the study, acquisition of data and analysis and interpretation of data; (2) drafting the article; and (3) final approval of the version submitted.

• References

• 1 Rossi R, Rosso F, Cottino U, Dettoni F, Bonasia DE, Bruzzone M. Total knee arthroplasty in the valgus knee. Int Orthop 2014; 38 (02) 273-283
• 2 Engh GA. The difficult knee: severe varus and valgus. Clin Orthop Relat Res 2003; 416: 58-63
• 3 Lombardi Jr AV, Dodds KL, Berend KR, Mallory TH, Adams JB. An algorithmic approach to total knee arthroplasty in the valgus knee. J Bone Joint Surg Am 2004; 86-A (Suppl. 02) 62-71
• 4 Ranawat AS, Ranawat CS, Elkus M, Rasquinha VJ, Rossi R, Babhulkar S. Total knee arthroplasty for severe valgus deformity. J Bone Joint Surg Am 2005; 87 (Pt 2, Suppl 1): 271-284
• 5 Alesi D, Meena A, Fratini S. et al. Total knee arthroplasty in valgus knee deformity: is it still a challenge in 2021?. Musculoskelet Surg 2022; 106 (01) 1-8
• 6 Sterneder CM, Faschingbauer M, Haralambiev L, Kasparek MF, Boettner F. Why kinematic alignment makes little sense in valgus osteoarthritis of the knee: a narrative review. J Clin Med 2024; 13 (05) 1302
• 7 Williot A, Rosset P, Favard L, Brilhault J, Burdin P. Total knee arthroplasty in valgus knee. Orthop Traumatol Surg Res 2010; 96: S37-S42
• 8 Favorito PJ, Mihalko WM, Krackow KA. Total knee arthroplasty in the valgus knee. J Am Acad Orthop Surg 2002; 10 (01) 16-24
• 9 Elorza SP, O'Donnell E, Nedopil AJ, Howell SM, Hull ML. A new tibial insert design with ball-in-socket medial conformity and posterior cruciate ligament retention closely restores native knee tibial rotation after unrestricted kinematic alignment. J Exp Orthop 2023; 10 (01) 115
• 10 Nicolet-Petersen S, Saiz A, Shelton T, Howell S, Hull ML. Kinematically aligned TKA restores physiological patellofemoral biomechanics in the sagittal plane during a deep knee bend. Knee Surg Sports Traumatol Arthrosc 2020; 28 (05) 1497-1507
• 11 Nedopil AJ, Howell SM, Hull ML, Hirschmann MT. A TKA can be kinematically aligned without restrictions: current evidence. Knee Surg Sports Traumatol Arthrosc 2024; 32 (06) 1354-1358
• 12 Roth JD, Howell SM, Hull ML. Tibial forces are more useful than varus-valgus laxities for identifying and correcting overstuffing in kinematically aligned total knee arthroplasty. J Orthop Res 2021; 39 (06) 1271-1280
• 13 Nedopil AJ, Howell SM, Hull ML. More passive internal tibial rotation with posterior cruciate ligament retention than with excision in a medial pivot TKA implanted with unrestricted caliper verified kinematic alignment. Knee Surg Sports Traumatol Arthrosc 2023; 31 (03) 852-860
• 14 Nedopil AJ, Howell SM, Hull ML. Deviations in femoral joint lines using calipered kinematically aligned TKA from virtually planned joint lines are small and do not affect clinical outcomes. Knee Surg Sports Traumatol Arthrosc 2020; 28 (10) 3118-3127
• 15 Johnson JM, Mahfouz MR, Midillioğlu MR, Nedopil AJ, Howell SM. Three-dimensional analysis of the tibial resection plane relative to the arthritic tibial plateau in total knee arthroplasty. J Exp Orthop 2017; 4 (01) 27
• 16 Nedopil AJ, Singh AK, Howell SM, Hull ML. Does calipered kinematically aligned TKA restore native left to right symmetry of the lower limb and improve function?. J Arthroplasty 2018; 33 (02) 398-406
• 17 Nedopil AJ, Howell SM, Hull ML. Measurement of tibial orientation helps select the optimal insert thickness to personalize PCL tension in a medial ball-in-socket TKA. J Pers Med 2022; 12 (09) 1427
• 18 Ewald FC. The Knee Society total knee arthroplasty roentgenographic evaluation and scoring system. Clin Orthop Relat Res 1989; 248: 9-12
• 19 Meneghini RM, Mont MA, Backstein DB, Bourne RB, Dennis DA, Scuderi GR. Development of a modern knee society radiographic evaluation system and methodology for total knee arthroplasty. J Arthroplasty 2015; 30 (12) 2311-2314
• 20 Kohn MD, Sassoon AA, Fernando ND. Classifications in brief: Kellgren-Lawrence classification of osteoarthritis. Clin Orthop Relat Res 2016; 474 (08) 1886-1893
• 21 Farooq H, Deckard ER, Carlson J, Ghattas N, Meneghini RM. Coronal and sagittal component position in contemporary total knee arthroplasty: targeting native alignment optimizes clinical outcomes. J Arthroplasty 2023; 38 (7, Suppl 2): S245-S251
• 22 Nedopil AJ, Howell SM, Hull ML. What clinical characteristics and radiographic parameters are associated with patellofemoral instability after kinematically aligned total knee arthroplasty?. Int Orthop 2017; 41 (02) 283-291
• 23 Clement ND, Scott CEH, Hamilton DF, MacDonald D, Howie CR. Meaningful values in the Forgotten Joint Score after total knee arthroplasty. Bone Joint J 2021; 103-B [phone]
• 24 Baumann F, Ernstberger T, Loibl M, Zeman F, Nerlich M, Tibesku C. Validation of the German Forgotten Joint Score (G-FJS) according to the COSMIN checklist: does a reduction in joint awareness indicate clinical improvement after arthroplasty of the knee?. Arch Orthop Trauma Surg 2016; 136 (02) 257-264
• 25 Cho H-J, Kwak D-S. Mechanical properties and characteristics of the anterolateral and collateral ligaments of the knee. Appl Sci (Basel) 2020; 10: 6266
• 26 Robinson JR, Bull AM, Amis AA. Structural properties of the medial collateral ligament complex of the human knee. J Biomech 2005; 38 (05) 1067-1074
• 27 Wijdicks CA, Ewart DT, Nuckley DJ, Johansen S, Engebretsen L, Laprade RF. Structural properties of the primary medial knee ligaments. Am J Sports Med 2010; 38 (08) 1638-1646
• 28 Fishkin Z, Miller D, Ritter C, Ziv I. Changes in human knee ligament stiffness secondary to osteoarthritis. J Orthop Res 2002; 20 (02) 204-207
• 29 Hayashi K. Biomechanical studies of the remodeling of knee joint tendons and ligaments. J Biomech 1996; 29 (06) 707-716
• 30 Robinson JR, Bull AMJ, Thomas RR, Amis AA. The role of the medial collateral ligament and posteromedial capsule in controlling knee laxity. Am J Sports Med 2006; 34 (11) 1815-1823
• 31 Brilhault J, Preyssas P, Favard L, Burdin P. Dimensions of the lateral condyle in non-arthritic valgus knees. A cadaver study. Rev Chir Orthop Repar Appar Mot 2002; 88 (07) 686-690
• 32 Rougereau G, Pujol N, Langlais T, Boisrenoult P. Is lateral femoral condyle hypoplasia a feature of genu valgum? A morphological computed tomography study of 200 knees. Orthop Traumatol Surg Res 2023; 109 (04) 103582
• 33 Shah R, Vail T, Bini S. The lateral femoral condyle is not hypoplastic relative to the medial condyle in 6829 magnetic resonance images irrespective of gender, age, or extent of arthritis. . J Orthopaedic Experience Innovation 2023
• 34 Karasavvidis T, Pagan Moldenhauer CA, Haddad FS, Hirschmann MT, Pagnano MW, Vigdorchik JM. Current concepts in alignment in total knee arthroplasty. J Arthroplasty 2023; 38 (7, Suppl 2): S29-S37
• 35 MacDessi SJ, Griffiths-Jones W, Harris IA, Bellemans J, Chen DB. Coronal plane alignment of the knee (CPAK) classification: a new system for describing knee phenotypes. Bone Joint J 2021; 103-B [phone]
• 36 Gill JR, Corbett JA, Wastnedge E, Nicolai P. Forgotten Joint Score: comparison between total and unicondylar knee arthroplasty. Knee 2021; 29: 26-32
• 37 Kleeblad LJ, Borus TA, Coon TM, Dounchis J, Nguyen JT, Pearle AD. Midterm survivorship and patient satisfaction of robotic-arm-assisted medial unicompartmental knee arthroplasty: a multicenter study. J Arthroplasty 2018; 33 (06) 1719
• 38 Shelton TJ, Nedopil AJ, Howell SM, Hull ML. Do varus or valgus outliers have higher forces in the medial or lateral compartments than those which are in-range after a kinematically aligned total knee arthroplasty? limb and joint line alignment after kinematically aligned total knee arthroplasty. Bone Joint J 2017; 99-B (10) 1319-1328
• 39 Verstraete MA, Meere PA, Salvadore G, Victor J, Walker PS. Contact forces in the tibiofemoral joint from soft tissue tensions: implications to soft tissue balancing in total knee arthroplasty. J Biomech 2017; 58: 195-202
• 40 Howell SM, Gill M, Shelton TJ, Nedopil AJ. Reoperations are few and confined to the most valgus phenotypes 4 years after unrestricted calipered kinematically aligned TKA. Knee Surg Sports Traumatol Arthrosc 2022; 30 (03) 948-957
• 41 Rak D, Klann L, Heinz T. et al. Influence of mechanical alignment on functional knee phenotypes and clinical outcomes in primary TKA: a 1-year prospective analysis. J Pers Med 2023; 13 (05) 778
• 42 Rak D, Rügamer T, Klann L, Nedopil AJ, Rudert M. Setting the distal and posterior condyle of the femoral component to restore the medial pre-arthritic femoral articular surface results in better outcomes after total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 2023; 31 (12) 5319-5331
• 43 Nedopil AJ, Shekhar A, Howell SM, Hull ML. An insert with less than spherical medial conformity causes a loss of passive internal rotation after calipered kinematically aligned TKA. Arch Orthop Trauma Surg 2021; 141 (12) 2287-2294
• 44 Pasqualini I, Piuzzi NS. Patient-reported outcome measures: state of the art in patient-reported outcome measure application in lower extremity orthopaedics. J Am Acad Orthop Surg 2023; 31 (20) e883-e889

Publikationsverlauf

Eingereicht: 13. Juni 2024

Angenommen: 19. August 2024

Accepted Manuscript online:
20. August 2024

Artikel online veröffentlicht:
27. September 2024