Outcomes of Medial Closing-Wedge Distal Femoral Osteotomy for Femoral- and Tibial-Based Valgus Deformity

Abstract

Background:

In carefully selected patients with an arthritic valgus knee, distal femoral osteotomy (DFO) can improve symptoms at medium- to long-term follow-up, reducing osteoarthritis progression. To date, there is no clear evidence in the current literature regarding the role of postoperative joint line obliquity (JLO) in valgus deformity correction.

Purpose:

To assess the clinical and radiological outcomes of medial closing-wedge DFO (MCW-DFO) for the treatment of valgus knees, considering both tibial- and femoral-based deformities, as well as to verify the efficacy and safety of MCW-DFO according to JLO boundaries (≤4°).

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A retrospective analysis was conducted on a cohort of patients with valgus knees. Patients were divided into 2 groups: femoral-based valgus (FB-V) and tibial-based valgus (TB-V). Knee radiographs were collected before surgery and at the last follow-up. The clinical outcome was evaluated through several validated scores (International Knee Documentation Committee, Knee Society Score, Knee injury and Osteoarthritis Outcome Score, Tegner, Numeric Rating Scale, Crosby-Insall).

Results:

A total of 30 patients (34 knees) with a mean age of 49.3 ± 9.1 years were included in the study. The overall mean follow-up was 9.4 ± 5.9 years. The mean preoperative hip-knee-ankle angle was 187.6°± 3.3° (range, 181.5°-191°) and the postoperative angle was 180°± 3.1° (range, 176°-185°). Most postoperative JLOs were within the safe zone of ≤4° in both groups (the postoperative JLO was >4° in 4 patients in the TB-V group and 1 patient in the FB-V group), although FB-V knees exhibited significant superior JLO correction (postoperative JLO in the TB-V group: mean, 4.0°± 2.5° [P = .1]; postoperative JLO in the FB-V group: mean, 2.4°± 1.4° [P = .5]). Significant improvements in all clinical scores were observed in both groups (P < .01). Additionally, the severity of the osteoarthritis did not worsen at the last follow-up.

Conclusion:

MCW-DFO is an effective procedure for treating pathological valgus knees, regardless of the site of the deformity. Both FB-V and TB-V groups showed comparable improvements in the clinical scores, development of osteoarthritis, and the restoration of a neutral mechanical axis. Notably, FB-V knees achieved more JLO correction compared with the TB-V ones.

Keywords

knee distal femoral osteotomy joint line obliquity radiographs lower limb alignment

Lower limb malalignments have been shown to increase the risk of subsequent medial or lateral knee osteoarthritis.²⁹ Valgus malalignment is defined as a lower limb in which the mechanical axis passes lateral to the knee joint center, and according to the literature, it occurs less frequently than varus deformity.⁴ Valgus knee malalignment can be femoral or tibial based.

It is widely known that in carefully selected patients with an arthritic valgus knee, distal femoral osteotomy (DFO) can improve symptoms at medium- to long-term follow-up, reducing osteoarthritis progression.^9,14,32

In the past few years, there has been an increasing focus on the role of joint line obliquity (JLO) in the outcomes of the alignment correction osteotomies.^{12,15,19,24,30} Moreover, in the context of varus malalignment, some studies have highlighted the need that the osteotomy should be performed at the level of the deformity to improve radiological and clinical outcomes.^21,25

To date, there is no clear evidence in the current literature regarding the role of postoperative JLO in valgus deformity correction. Furthermore, the need to correct the valgus malalignment at the level of the deformity has not been defined. Thus, this study focused on medial closing-wedge DFO (MCW-DFO) as a treatment for pathological valgus malalignment, considering both femoral- and tibial-based deformity. The aim of the study was to assess the safety and efficacy of MCW-DFO for both femoral- and tibial-based deformity according to the JLO boundaries. The secondary goal was to evaluate the clinical scores and radiological parameters to compare the efficacy of MCW-DFO in the treatment of a femoral-based valgus (FB-V) knee and tibial-based valgus (TB-V) knee.

We hypothesized that JLO remains within safe boundaries (≤4°) when treating both FB-V and TB-V knees with MCW-DFO. We also hypothesized that there are no clinical and radiographic differences using MCW-DFO for both groups.

Methods

A retrospective analysis was conducted on a cohort of 44 patients (48 knees) with pathological valgus knees, regardless of the origin (femoral- or tibial-based deformity), who underwent MCW-DFO. All the surgeries were performed by a senior knee surgeon (M.B.) between 2001 and 2020 in our department.

The following inclusion criteria were adopted: presence of symptomatic lateral overload or osteoarthritis (Kellgren-Lawrence grades I-III) with a valgus alignment (hip-knee-ankle angle [HKA] of 182° to 195°), pre- and postoperative radiographs (anteroposterior weightbearing long-leg, standard weightbearing knee views), age ≥16 years at the time of surgery, and a minimum follow-up of 2 years after surgery. Patients were excluded from participation in the study in cases of previous osteotomies on the same limb, previous fractures of the same limb, ipsilateral hip prosthesis, and extension of osteoarthritis to the medial or patellofemoral compartments as a contraindication to the osteotomy procedure. Patients with an HKA >195° were excluded from the study because either a double-level or a 2-stage osteotomy or an external fixation system was indicated to avoid an excessive joint line inclination and to reduce the risk of intraoperative fractures or hypocorrections of the deformity.

The surgical technique consisted of an MCW-DFO fixed with a plate and screws (TomoFix MDF; DePuy Synthes). Preoperatively, all osteotomies were planned as described by Miniaci, aiming to shift the mechanical axis so that it falls through the center or just medial to the center of the knee.¹⁸

The clinical outcome was evaluated at the baseline and at the last follow-up through several validated scores: Knee Society Score (KSS; objective and functional scores), International Knee Documentation Committee (IKDC) Subjective Knee Form, Knee injury and Osteoarthritis Outcome Score (KOOS), Tegner activity scale, and the numeric rating scale for pain (NRS).^{11,13,17,23,31} The overall patient satisfaction was collected according to the Crosby-Insall grading system⁷ at the final follow-up, while peri- or postoperative complications and failures were registered throughout the study period. Patients were then divided into 2 groups, FB-V and TB-V, depending on the location of the deformity, measured as a lateral distal femoral angle (LDFA) <85° or medial proximal tibial angle (MPTA) >90° before the operation. Standing long-leg and knee radiographs were collected for each patient before surgery and at last follow-up to assess the grade of knee osteoarthritis (Kellgren-Lawrence), the lower limb alignment (HKA), the JLO angle, and the joint line congruency angle (JLCA).

The study was designed based on the criteria of the Declaration of Helsinki and approved by the local ethics committee (IRB No. IOGP2019MBPSR1 Version 1).

Radiographic Measurements

Long-leg anteroposterior weightbearing radiographs and weightbearing knee radiographs (anteroposterior and lateral views) were collected pre- and postoperatively using the same picture archiving and communication system (AGFA Impax 6.0) for every patient (Figure 1). Different angles were measured:

HKA: Angle between the line from the center of the femoral head to the center of the knee joint and the line from the center of the knee to the center of the ankle joint (angle measured medially).

MPTA: Angle between the line tangent to the tibial plateau and the mechanical axis of the tibia. Values >90° were considered suggestive of TB-V deformity.

Mechanical LDFA: Angle between the line tangent to distal femoral condyles and the mechanical axis of the femur. Values <85° were considered suggestive of an FB-V deformity.

JLO angle: Angle between the line tangent to the tibial plateau and the line parallel to the ground. This angle was considered in the safe zone if ≤4°.³⁰

JLCA: Angle between a line tangent to distal femoral condyles and a line tangent to the proximal tibial plateau. If the angle opens medially, it is considered suggestive of an intra-articular deformity.

To determine intra- and interobserver reliability of radiographic assessments, the measurements were perfomed twice, at a 2-month interval, by 2 orthopaedic surgeons (A.M., F.C.) not involved in the surgical procedure. The intra- and interobserver reliability of the radiographic measurements were evaluated using intraclass correlation coefficients (ICCs) using an absolute-agreement, 2-way mixed-effects model. According to the ICC values proposed by Koo and Li,¹⁶ the reliability was defined as poor (<0.5), moderate (0.5 ≤ ICC < 0.75), good (0.75 ≤ ICC < 0.90), or excellent (≥0.90).

Surgical Technique

Diagnostic arthroscopy was performed before the osteotomy to assess any chondral or meniscal tears. After arthroscopy, the patient was positioned supine with the knee semiflexed to 30°; the tourniquet was positioned but not inflated. A 7-cm skin incision was made medially on the distal thigh proximal to the medial epicondyle. The crural fascia was incised longitudinally, and the septum between the sartorius muscle and the vastus medialis muscle was identified. Subsequently, blunt dissection to the femur with elevation of the vastus medialis muscle was performed using a Hohmann retractor. The intermuscular septum was incised posteriorly to the femur and dissected from distal to proximal. The periostium was incised and 4 K-wires were positioned, creating a cage, the base of which was the height calculated on the preoperative planning. The hinge point was chosen just proximal to the posterior condyles at the lateral cortex and was protected by a No. 3 K-wire. Under protection of a Blount retractor, the transverse arm of the osteotomy was performed. The ascending osteotomy was performed for approximately 3 to 5 cm. The bone wedge was then removed, and the osteotomy closed accurately, taking care to avoid torsion and excessive pressure. The plate (TomoFix MDF) was positioned on the bone and first fixed distally with four 5.0 angular locking screws (LSs) and then proximally under image intensifier control. In the first proximal hole, a bicortical eccentrically drilled cortical screw was inserted, allowing compression on the osteotomy site. Once compression was reached, the plate was fixed proximally with a bicortical 5.0 LS. At the end, the golden screw was replaced by a 5.0 LS. A final radiological evaluation under image intensifier of the knee was performed to verify accurate plate positioning. A drain was placed.

The postoperative rehabilitation protocol began from the day after surgery, when active and passive range of motion exercises and straight leg raising exercises were started. Partial weightbearing was allowed from 1 week after surgery, and full weightbearing was allowed from 2 weeks after surgery. Casts or braces were not used. Return-to-sports activities, including jogging or hard work, were permitted after bony union at the osteotomy site was verified by radiographs, but not before 6 months.

Statistical Analysis

Statistical analysis was performed using R statistical software (Version 4.0.0; R Foundation for Statistical Computing) and GraphPad Prism Version 6.0 software (GraphPad Software Inc). The Shapiro-Wilk normality test was used to evaluate the normal distribution of the sample. Continuous variables are expressed as mean ± standard deviation and median [first quartile, third quartile]. Categorical variables are expressed in numbers of cases and frequencies; their differences were tested using with the chi-square test or Fisher exact test.

The between-group differences for continuous variables were evaluated with the unpaired Student t test or Mann-Whitney test, while the within-group differences from baseline to final follow-up for continuous variables were evaluated with the paired t test or Wilcoxon matched-pairs signed-rank test, according to the characteristics of the data distribution. For all analyses, the significance level was set at a P value <.05. Data were treated and analyzed as continuous variables; the results where then split in categories for an easier interpretation of the results.

Results

Among a cohort of 44 patients (48 knees) with pathological valgus knees treated with a femoral osteotomy, 30 patients (34 knees) with a mean age of 49.3 ± 9.1 years were included in the study after inclusion and exclusion criteria were applied. The FB-V group included 16 patients (17 knees) and the TB-V group included 15 patients (17 knees); 1 patient was in both groups. No patient in the FB-V group had an MPTA >90°, and no patient in the TB-V group had an LDFA <85°. In no case was a double-level osteotomy (DLO) required. The 1 patient in both groups was treated with femoral osteotomy despite having a valgus knee of tibial origin on one side and a valgus knee of femoral origin on the contralateral side. He had no significant clinical or radiographic differences between the 2 knees. This patient was counted as a member of both the FB-V group and the TB-V group. Therefore, the TB-V group consisted of 15 patients and the FB-V group consisted of 16 patients, although the total number of patients analyzed was 30. The flowchart of patient selection and the study population characteristics are available in Figure 2 and Table 1, respectively. The overall mean follow-up was 9.48 ± 5.93 years (mean follow-up in TB-V group, 8.02 ± 4.94 vs FB-V group, 10.93 ± 6.61 years).

Table 1

Patient Characteristics^a

	Overall	FB-V Group	TB-V Group
No. of patients	30	16	15
No. of knees	34	17	17
Mean follow-up, y	9.4 ± 5.9, 8.2 [4.4-12.0]	10.9 ± 6.6, 10.2 [6.6-12.4]	8 ± 4.9, 5.4 [4.1-11.4]
Age at surgery, y	49.3 ± 9.1, 52.5 [45.0-54.7]	47.4 ± 9.8, 50 [44-53]	51.2 ± 8.1, 53 [51-55]
Sex
Male	22 (73.3)	11 (36.6)	11 (36.6)
Female	8 (26.7)	5 (16.6)	4 (13.3)
BMI	26.3 ± 3.9, 26.4 [23.3-29.1]	26.6 ± 4.1, 26.7 [24.0-28.7]	26.1 ± 3.8, 25.6 [23.1-29.8]
Smoking	9/30 (30.0)	5/30 (16.7)	5/30 (16.7)

Data are expressed as mean ± SD, median [Q1-Q3], or n (%). One patient was in both groups with 1 FB-V knee and 1 TB-V knee. BMI, body mass index; FB-V, femoral-based valgus; TB-V, tibial-based valgus.

Arthroscopic treatment of associated lesions was performed in 5 patients (3 lateral partial meniscectomy procedures, 1 lateral parameniscal cyst drainage, and 1 patellar microfracture). The mean overall HKA before surgery was 187.6°± 3.3° (range, 181.5°-191°). All clinical scores showed a significant improvement (P < .01) in both groups compared with before the intervention, with no statistical difference between the TB-V and FB-V groups (P > .05).

Preoperative JLO did not differ between the 2 groups (2.8°± 2.1° in the TB-V group vs 2.2°± 2.5° in the FB-V group; P > .05). Most postoperative values of JLO were in the safe zone (≤4°); however, the postoperative JLO was >4° in 4 patients of the TB-V group (range, 0°-7.5°) and in 1 patient of the FB-V group (range, 0°-5.5°). FB-V knees exhibited significantly superior JLO correction (mean postoperative JLO, 2.4°; 95% CI, 1.64 -3.17) (P = .5) compared with TB-V knees (mean postoperative JLO, 4°; 95% CI, 2.78- 5.81) (P = .1).

The postoperative LDFA in the TB-V group was 92.1°± 3.9° (90.0°± 2.3° in the FB-V group) (ΔP = .05), while the postoperative MPTA in the TB-V group remained 92.8°± 1.6° (88.8°± 1.8° in the FB-V group) (ΔP < .0001). These results showed that in the TB-V group, the femur became varus while the tibia remained valgus, whereas in the FB-V group, both the LDFA and MPTA were found to be in the normal range of values.

The JLCA was reported with a significant difference between the preoperative and postoperative period (P < .01) in the TB-V group, unlike the FB-V group, in which the difference between the pre- and postoperative period was not statistically significant (P > .05). The difference between the postoperative JLCA values in the 2 groups was found to be significant (P < .05), emphasizing greater correction of joint convergence in the tibial group. Additionally, the severity of the osteoarthritis did not worsen at the last follow-up, and restoration of a neutral mechanical axis was achieved in both groups (mean HKA, 179.2°± 2.5° for the FB-V group vs 180.8°± 2.8° for the TB-V group).

Significant improvements in all clinical scores compared with baseline were observed in both groups (P < .01), confirming the achievement of a good knee function and activity level, but with no difference between the 2 phenotypes. Patient satisfaction was rated as good in most of the cases, specifically in 12 knees (70.6%) in the TB-V group and 14 knees (82.4%) in the FB-V group.

Considering the patients in whom a postoperative JLO value >4° was reported, the clinical results showed a significant improvement for all scores (P < .05) in both groups: the overall IKDC score went from 43.3 ± 15.2 to 72 ± 20.2; the overall KSS objective and functional scores changed from 51.4 ± 16 to 81.4 ± 23.1 and from 53 ± 11.5 to 81 ± 24, respectively; the overall KOOS went from 45.1 ± 13 to 83.3 ± 16.2; the Tegner activity scale showed an improvement from 3.6 ± 2.5 to 4 ± 1.8; and the NRS changed from 61 ± 18.8 to 16 ± 20.7. Finally, the overall satisfaction rate was also good in this subgroup of patients. Complete data about the clinical and radiological outcomes are reported in Table 2.

Table 2

Comparison of the Radiological Measurements and Clinical Outcome, at Baseline and Last Follow-up, Between the 2 Groups^a

	TB-V Group	FB-V Group	P Value
HKA, deg
Preoperative	188.4 ± 3.0 (range, 181.5-193.5)	186.9 ± 3.4 (range, 182-194)	.1602
Last FU	180.8 ± 2.8 (range, 176-185)	179.2 ± 2.5 (range, 176-185)	.0966
P value	<.0001	<.0001
MPTA, deg
Preoperative	92.8 ± 1.5	88.9 ± 1.6	<.0001
Last FU	92.8 ± 1.6	88.8 ± 1.8	<.0001
P value	>.9999	.5
LDFA, deg
Preoperative	85.2 ± 2.6	83.5 ± 2.7	.0706
Last FU	92.1 ± 3.9	90.0 ± 2.3	.0586
P value	<.0001	<.0001
JLO angle, deg
Preoperative	2.8 ± 2.1	2.2 ± 2.5	.2821
Last FU	4.0 ± 2.5	2.4 ± 1.4	.0266
P value	.1597	.5959
JLCA, deg
Preoperative	1.9 ± 1.3	2.3 ± 2.5	.9172
Last FU	1 ± 1.1	2.4 ± 1.4	.0082
P value	.0066	.7251
Osteoarthritis^b
Preoperative	2.4 ± 0.5	2.1 ± 0.9	.7682
Last FU	2.5 ± 0.7	2.4 ± 1.1	.9416
P value	.5	.125
KSS objective
Preoperative	48.2 ± 12.9	49.0 ± 15.2	.8545
Last FU	83.1 ± 19.1	75.0 ± 15.2	.8911
P value	<.0001	<.0001
KSS functional
Preoperative	48.2 ± 12.9	47.3 ± 13.0	.8438
Last FU	83.1 ± 19.1	81.8 ± 20.1	.8831
P value	<.0001	<.0001
IKDC score
Preoperative	39.6 ± 9.9	45.3 ± 15.3	.3349
Last FU	63.8 ± 15.5	63.1 ± 18.8	.9088
P value	<.0001	.0002
KOOS
Preoperative	46.3 ± 11.7	48.1 ± 12.5	.6735
Last FU	79.9 ± 12.6	81.1 ± 10.3	.7674
P value	<.0001	<.0001
Tegner score
Preoperative	2	3	.4155
Last FU	4	4	.3147
P value	.001	.0045
NRS score
Preoperative	69.1 ± 22.6	63.5 ± 17.2	.1895
Last FU	37.6 ± 27.8	33.5 ± 21.3	.6017
P value	.0001	<.0001
Crosby-Insall grade
Last FU	Good	Good

Data are expressed as mean ± SD, except for the Tegner and Insall-Crosby scores, which are expressed in median values. A statistically significant difference was achieved with a P value ≤.05. FB-V, femoral-based valgus; FU, follow-up; HKA, hip-knee-ankle angle; IKDC, International Knee Documentation Committee; JLCA, joint line congruency angle; JLO, joint line obliquity; KOOS, Knee injury and Osteoarthritis Outcome Score; KSS, Knee Society Score; LDFA, lateral distal femoral angle; MPTA, medial proximal tibial angle; NRS, numeric rating scale for pain; TB-V, tibial-based valgus.

Measured by the Kellgren-Lawrence grading system.

Regarding the intraoperative complications, 1 hinge fracture occurred in a patient in the TB-V group, who then experienced hypertrophic nonunion and underwent a revision 3 years after the osteotomy (device removal, gap filling with synthetic bone graft, and new fixation with double plating and screws). One patient in the same group was diagnosed with psoriatic arthritis after surgery with no influence on the clinical results. In the FB-V group, one patient developed anemia and thrombocytopenia after the operation, resulting in a longer hospital stay, while in another patient a transient neurologic palsy of the saphenous nerve was reported with a complete recovery within 6 months with a supply of neurotrophic drugs. No secondary displacements or loss of correction were detected. During the whole follow-up period, only 1 conversion to total knee arthroplasty (TKA; 2.9%) was recorded in the TB-V group, 14 years after the osteotomy, while 2 patients in the FB-V group underwent an arthroscopic debridement 1 and 9 years after the procedure because of pain and joint stiffness, respectively.

Discussion

The most important finding of this study is that MCW-DFO allows us, in most cases, to obtain a lateral JLO within tolerance limits (≤4°) regardless of the site of the deformity responsible for a valgus malalignment up to 15°, without affecting long-term radiographic and especially clinical outcomes. To our knowledge, this represents one of the studies with the longest follow-up in evaluating the treatment of valgus knee with a DFO, and the 2 comparison groups (TB-V and FB-V) allow us to draw definite considerations.

The postoperative JLO parameter has been extensively debated in recent times, and the value of its limit remains controversial. Over time in the literature, its value has changed from 10° to 4° and then to 5°.^2,6,26 Finally, in 2020, Song et al³⁰ proposed 4° as an acceptable limit, with worsening clinical and radiographic findings beyond 6°. According to Nakayama et al,¹⁹ a nonanatomic JLO >5° after high tibial osteotomy (HTO) leads to a double increase of the shear stress on the medial compartment with a risk of early failure. However, most studies have been conducted on tibial osteotomies (especially OW-HTO), and to date there is a lack of studies concerning JLO in femoral osteotomies.^{1,15,19-21,24,30}

According to the recent European Society for Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA) consensus recommendations, to achieve good results after knee osteotomy surgery, it is advisable to correct the deformity where it is located, to avoid creating a new one without correcting the present one.⁸ In fact, in the past, this dogma has not always been respected and lower limb valgus alignment was often corrected by acting on the femur, regardless of the site of the deformity.

Therefore, the present study has considered 2 groups of patients: the FB-V group, in which a medial femoral osteotomy was performed to treat a valgus femoral deformity, and the TB-V group, in which the same procedure was used to correct the valgus tibial one. The comparison revealed that, with the same degree of preoperative HKA and lateral osteoarthritis, within the bounds set forth in this study, there were no significant differences between the 2 groups in terms of clinical outcomes, as well as in terms of the worsening of the osteoarthritic condition and the restoration of a physiological axis of the lower limb. The only significant difference observed concerns postoperative JLO correction, which appeared to be higher (mean, 2°) in the FB-V group than in the TB-V group (mean, 4°), although both were still contained within the boundaries of tolerance as described by other authors.

Ollivier et al²⁰ recently scanned 129 patients who underwent medial OW-HTO for symptomatic isolated medial knee osteoarthritis using a software designed to observe the percentage of risk to exceed ESSKA recommendations in the postoperative phase. The authors showed that a DLO would have been suitable in 17.8% of patients and a DFO in 27.9% to avoid a postoperative tibial overcorrection, which results in an increased JLO. The authors, however, did not correlate these data to clinical outcomes. Akamatsu et al¹ compared clinical, radiologic, and arthroscopic outcomes of varus knees treated with OW-HTO alone and DLO (34 patients per group at 2 years of follow-up) and reported a significant change of the JLO only in the OW-HTO group, from 1.4° to 6.3° (P < .001), without clinical or arthroscopic implications.

Recently, Schröter et al²⁷ demonstrated how a postoperative LDFA >90° after DFO correlates with lower clinical outcomes in terms of the Hospital for Special Surgery score and Lysholm score, compared with patients with LDFA <90°. This study considered 52 patients with a mean follow-up of 70.3 months. In another study, Schröter et al²⁸ considered a target of LDFA <94° to be reasonable when correcting a valgus deformity. According to our results, there were no significant differences between TB-V and FB-V in terms of IKDC score, KOOS, Tegner score, and osteoarthritis assessment at long-term follow-up, despite the LDFA of the TB-V group being a mean of 92.1°± 3.9° in the postoperative period, compared with 90.0°± 2.3° in the FB-V group. This probably occurred because the LDFA value remained within 4° of the upper normal limit (set at 90°).

The evidence seems to lean toward performing knee osteotomy at the level of the bony deformity. Recently Park et al²¹ demonstrated how JLO was more oblique in patients undergoing OW-HTO without a tibia vara (MPTA >85°) than in patients with an MPTA <85°. According to this study, this was correlated with the clinical outcomes (KSS and WOMAC) after a follow-up >2 years. According to our experience, however, no significant clinical or radiological differences were observed in DFO performed on knees with deformities of tibial origin (TB-V) or femoral origin (FB-V), considering cases with HKA <195°. In particular, the mean postoperative LDFA in the TB-V group was 92.1°± 3.9° (90.0°± 2.3° in the FB-V group), while the mean postoperative MPTA in the TB-V group remained 92.8°± 1.6° (88.8°± 1.8° in the FB-V group).

The mean postoperative JLO was found to be 4.0°± 2.5° in the TB-V group (2.4°± 1.4° in the FB-V group), thus remaining within the tolerance range. Indeed, this finding had no influence on the clinical results. Although the JLO in the group of TB-V knees was in most cases within the tolerance limits of 4°, in 4 cases a JLO beyond the limits was recorded without affecting the clinical results. Moreover, 1 case belonging to the FB-V group also showed a postoperative JLO >4° without showing worse results. In the long-term period, a JLO above the tolerance limits may lead to a possible early failure of the osteotomy with a conversion to TKA. Actually, in our study, the overall follow-up was 9.48 ± 5.93 years, and only 1 conversion to TKA was recorded. It occurred in the TB-V group, 14 years after the osteotomy, indicating that maybe the obliquity of the joint alone did not lead to a complete failure of the intervention.

All radiological measurement included in the present paper were evaluated by 2 fully trained orthopaedists with good interobserver reliability according to Koo and Li,¹⁶ (0.75 ≤ ICC < 0.90).

To perform an antivalgus osteotomy, the surgeon can act on the femur (medial closing wedge or lateral opening wedge) or on the tibia (proximal medial closing wedge), the latter choice being especially useful for small corrections.²² In our experience, the medial closing-wedge technique on the femoral side is preferred for several reasons, including the surgeon's preference (great experience in the long term), the small influence on postoperative JLO, and an excellent muscle coverage with faster healing.¹⁰ Few studies have been published concerning medial closing-wedge HTO (MCW-HTO) at long-term follow-up.^3,5 The longest report was performed by Chambat et al³ on 47 patients at a mean follow-up of 7 years. Unlike DFO, the great advantage of the MCW-HTO is the effect on the joint in both extension and flexion, although it carries the risk of potential excessive JLO >10° and difficult intraoperative fine-tuning, which have reduced its widespread use over time.

This study has several limitations that should be considered. First, the study has a retrospective design, with a consequent lack of randomization and derived bias. Moreover, the relatively small pool of patients included within each group necessarily limited the analysis of the relation between clinical and radiological outcomes and influencing factors. It should be considered, however, that strict surgical indications may have influenced the said limitations. Third, the indication for femoral osteotomy even in cases of valgus of tibial origin (TB-V group) runs counter to the recent recommendations,^8,21,25 such as correcting at the site of the deformity to avoid new deformities and acting on the tibia to control the correction of malalignment in the coronal and sagittal plane, but considers patients who had already undergone surgery following the surgeon's technique preference.

On the other hand, the main strength of this study is the direct comparison between 2 groups (TB-V and FB-V) of patients undergoing the same DFO, with homogeneous characteristics in terms of number of patients, age, sex, axial alignment, and years of follow-up. To our knowledge, there are no studies evaluating both clinical and radiological outcomes and osteoarthritis progression through a comparison between patients treated with MCW-DFO, regardless of the origin of the valgus knee.

Conclusion

MCW-DFO is an effective procedure for treating pathological valgus knees, regardless of the site of the deformity; indeed, our data confirm that there is no evidence of difference in results after treatment in the 2 groups of patients (valgus deformity on the tibial or femoral site). Both FB-V and TB-V groups showed comparable improvements in clinical scores, development of osteoarthritis, and restoration of a neutral mechanical axis. Notably, FB-V knees achieved more JLO correction than the TB-V ones.

Footnotes

Submitted December 19, 2023; accepted May 3, 2024.

The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

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