Around-the-knee osteotomies part 1: definitions, rationale and planning-state of the art

Safe Sawing Conditions to Prevent Popliteal Artery Injury in Various Distal Femoral Osteotomies: Three-dimensional Simulation Analysis

BACKGROUND

Distal femoral osteotomy (DFO) use is increasing in popularity, and popliteal artery injury during DFO can be devastating.

PURPOSE

To determine the safe sawing angles in DFO to prevent popliteal artery injury by analyzing the artery's course and the distances from key structures within the osteotomy plane.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Three-dimensional images of the healthy popliteal artery and femur were reconstructed from computed tomography angiography scans of 27 patients, and medial and lateral closing-wedge DFO (MCW-DFO and LCW-DFO) was simulated. Specifically, after formation of the osteotomy plane that passes the designated hinge point and primary cutting start point, the plane was rotated by 5° and 10° to create the 0°, 5°, and 10° osteotomy planes. Minimal distances to the popliteal artery from the posterior cortex and posterior cortical line (dPA-PC, dPA-PCL) were measured in each osteotomy plane. A distance <10 mm was defined as "at risk." Frontal safe sawing index (FSSI), maximal safe sawing angles (MSSAs), and maximal safe osteotomy angles (MSOAs) were analyzed to evaluate the safety margin.

RESULTS

The FSSI was significantly higher in MCW-DFO than LCW-DFO across all osteotomy planes (P < .001). In MCW-DFO, FSSI decreased with higher-degree upper cuts (P < .001), while in LCW-DFO, it was maintained. The mean minimal distance to the popliteal artery from the posterior cortex ranged from 13 to 14 mm in all DFO simulations. MCW-DFO and LCW-DFO showed a decrease in dPA-PC with higher-degree cuts (P < .001), and dPA-PCL was consistently shorter than dPA-PC (P < .001). The at-risk ratio of dPA-PCL was higher than that of dPA-PC in all conditions, favoring cutting along the normal curvature of the cortex over cutting straight. The MSSA for MCW-DFO was around 5°, with no significant variation between osteotomy planes. LCW-DFO had a smaller safety margin when compared with MCW-DFO, considering the 95% confidence interval of MSSAs. However, MSOA values were higher in LCW-DFO than MCW-DFO (P < .001). The dPA-PC was correlated with height, weight, body mass index, and transepicondylar distance (P < .05).

CONCLUSION/CLINICAL RELEVANCE

The safety margin during osteotomies in various DFO scenarios may vary. When DFO is performed, it is essential to be aware of safety tips related to the course of the popliteal artery and the normal curvature of the femoral posterior cortex.

Lateral closing wedge high tibial osteotomy procedure for the treatment of medial knee osteoarthritis: eleven years mean follow up analysis

PURPOSE

To assess long term survivorship, patient reported (PROMs) and radiological outcomes, and rate of adverse events and hardware removal after lateral closing wedge high tibial osteotomy (CWHTO) for the treatment of medial knee osteoarthritis (OA) and varus malalignment.

METHODS

Retrospective analysis of patients who underwent isolated CWHTO for medial OA in varus knee between 2009 and 2019 at the same institution was performed. Surgical failure was defined as conversion to total knee arthroplasty (TKA) or need for osteotomy revision procedure for varus recurrence, while clinical failure was defined by a Lysholm score under 65 points. Lysholm score, Visual Analogue Scale for pain (VAS), and patients' satisfaction with the treatment were evaluated. Radiographic parameters assessed included OA degree with the Kellgren Lawrence scale (KL), hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), joint line convergence angle (JLCA), and posterior tibial slope (PTS). Adverse events and rate of hardware removal procedures were recorded through follow up visits and clinical records. Survival analysis was conducted through Kaplan-Meier method with surgical and clinical failure as endpoints.

RESULTS

70 knees (mean age at surgery 43.3 years) were included in the survivorship analysis at a mean follow up of 11.6 ± 3.4 years. A failure rate of 12.85% (9/70) was recorded during the follow up period, with a survivorship of 92% and 75% at ten and 15 years of follow up, respectively. Mean Lysholm score and VAS at follow up were above the PASS threshold reported in literature. The 75.7% of patients were satisfied with the treatment. Radiological follow up indicated a residual mechanical varus of 2.1°, a decrease of 0.7° of intra articular deformity (JLCA), no change in PTS nor in KL index. The adverse events rate recorded was 5.7% (4/70). In nine knees (14.7%) among the patients survived from surgical failure a subsequent hardware removal procedure was performed.

CONCLUSION

CWHTO represents a safe procedure, which resulted in high survivorship (92% and 75% at ten and 15 years follow up, respectively), with satisfactory PROMs and radiological outcomes at long term follow up in patients affected by medial OA and varus malalignment.

LEVEL OF EVIDENCE

5, Case Series.

Altered motor function during daily activities in patients eligible for high tibial osteotomy is primarily driven by knee varus deformity

Aims

Patients with knee osteoarthritis (OA) and varus deformity present altered gait parameters, especially a large knee adduction moment that is predictive of OA progression. The distinct role of each coexisting parameter, such as OA grade, varus deformity, and previous meniscectomy, in the setting of high tibial osteotomy is not clear. Therefore, the aim of this study was to analyze the motor function parameters in patients eligible for high tibial osteotomy during walking, stair ascending, and stair descending, and to evaluate the effect of OA grade, varus deformity, and meniscectomy.

Methods

A total of 52 patients with knee OA and varus deformity participated in this study, including 22 with previous partial meniscectomy, alongside 20 healthy controls. Imaging and motion-capture data during walking, stair ascending, and descending were acquired. Subject characteristics, joint kinematics, joint kinetics, and electromyography on-off activities were compared to evaluate statistically significant differences between the patients and healthy groups. Additionally, multiple linear regression evaluated the relationships between OA grade, varus deformity, and previous meniscectomy with motor function parameters.

Results

The patients group showed significantly higher knee adduction and rotation moments, lower hip adduction and ankle inversion, and higher knee adduction and trunk flexion compared with the healthy group, as well as significantly increased biceps femoris activity. In addition, larger varus deformity showed a more marked effect on the major motor function parameters compared with OA grade and previous meniscectomy, especially during walking.

Conclusion

Patients eligible for high tibial osteotomy move with altered motor function during daily activities, and the coexisting factors of OA grade, varus malalignment, and previous meniscectomy have different impacts, with varus deformity primarily affecting motor function. These findings help to detect the target that should be considered priority in the treatment of high tibial osteotomy, and highlight the importance of realigning the lower limb to possibly restore motor function.

Mobile app-based monitoring of recovery after knee osteotomy: Patients take approximately five months to return to preoperative step counts despite limited app uptake

INTRODUCTION

This study aimed to assess the feasibility of using mobile application (app) technology for monitoring recovery after knee osteotomy and to determine the time required for patients to return to their preoperative step counts.

METHODS

This retrospective study included 329 patients who underwent coronal realignment surgery, including high tibial osteotomy (HTO) or distal femoral osteotomy (DFO) with a minimum follow-up of 1 year. The patients were grouped based on the type of osteotomy performed, i.e., HTO and DFO groups. Step count data were collected using the myrecovery app and analyzed preoperatively and at 1 month, 3 months, 6 months, and 12 months postoperatively. Statistical analyses included univariate linear regression models to assess the relationship between step counts at each time point and the duration required to return to their preoperative step counts.

RESULTS

Of the 329 patients included in the study, a total of 62 patients (19%) downloaded the app and 24 patients (7%) had complete step count data. Of the 24 patients with complete data, 18 were included in the HTO group and 6 were included in the DFO group. It took patients an average of 153 ​± ​112 days to return to their preoperative step counts, with the patients in the HTO group taking 174 ​± ​121 days and those in the DFO group taking 113 ​± ​77 days. Step counts increased significantly over time, with percentages of preoperative step counts reaching 108% at 12 months postoperatively. A statistically significant correlation was found between step counts at 3 months postoperatively and the time to return to preoperative step counts (R2 ​= ​0.240, P ​= ​0.015).

DISCUSSION

This study found that patients took approximately 5 months to return to their preoperative step counts after knee osteotomy. However, the adoption of the app was limited, with only 19% of patients downloading the app and just 7% providing complete data, posing a significant barrier to the feasibility of mobile apps for tracking recovery.

CONCLUSION

The mobile app is effective for tracking recovery progress following knee osteotomy, but strategies to increase patient adoption are essential for enhancing its practical application.

LEVEL OF EVIDENCE

Level IV, Retrospective Case Series.

The influence in clinical results of lower limb length discrepancy following distal femoral osteotomy

BACKGROUND

Distal femoral osteotomy (DFO) improves valgus limb alignment. However, it might affect lower limb length discrepancy (LLD) and influence functional scores. This study aims to evaluate functional scores and radiographic parameters associated with LLD after DFO.

HYPOTHESIS

It was hypothesized that the presence of LLD after DFO affects functional scores and associated with femoral length.

PATIENTS AND METHODS

A total of 50 patients who underwent DFO, including 24 closed wedge (CW) DFO and 26 open wedge (OW) DFO, were included. Patients were divided into three groups according to the presence of LLD after DFO: LLD-Absent group, LLD-CW group and LLD-OW group. Patient demographics, functional scores (Knee injury and Osteoarthritis Outcome Score (KOOS)), and radiographic parameters were evaluated and compared between the three groups. Multivariable logistic regression analysis was used to assess the radiographic parameter associated with the presence of post-operative LLD.

RESULTS

There were no significant differences between the three groups in demographic data, correction angles, complications including hinge fractures, time to osteotomy union, and functional scores. However, the return to sports (RTS) was significantly different between three groups. By further analysis between CWDFO and OWDFO, RTS in CWDFO was faster than those in OWDFO. There were significant differences in post-operative mLDFA and Δ femur length. Additionally, post-operative mLDFA was significantly associated with the presence of LLD (Odds ratio 0.11, 95% confidence interval 0.01 to 0.49, p = 0.03).

CONCLUSION

Functional scores and postoperative outcomes following DFO are not affected by the presence of LLD. RTS is independent of LLD, but rather dependent on the surgical procedure and RTS in CWDFO was faster than those in OWDFO. Postoperative mLDFA is the radiographic parameter associated with the presence of LLD. These findings are clinically relevant and should be accounted for in preoperative planning of DFO.

LEVEL OF EVIDENCE III

Retrospective with comparative study.

Stress Distribution Patterns of the Femorotibial Joint After Medial Closing-Wedge Distal Femoral Varus Osteotomy: An Evaluation Using Computed Tomography Osteoabsorptiometry

BACKGROUND

Distal femoral varus osteotomy (DFVO) is an established surgical procedure for addressing valgus malalignment across various knee conditions. However, the effect of DFVO on stress distribution within the femorotibial joint has not been explored through in vivo studies.

PURPOSE

To (1) explore the distribution pattern of subchondral bone density across the proximal tibia in nonarthritic knees without arthritis and in those of patients with valgus knees, (2) assess changes in the pattern of bone density distribution in patients with valgus knees before and after medial closing-wedge (MCW) DFVO, and (3) determine the correlation between leg alignment and changes in bone density distribution.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The authors retrospectively analyzed clinical and radiographic data from 14 patients (14 knees; mean age, 44 years; 3 men, 11 women) treated with MCW-DFVO for lateral compartment osteoarthritis (OA) due to valgus malalignment, alongside a control group of 18 patients (18 knees; mean age, 21 years; 4 men, 14 women) without OA. The distribution patterns of subchondral bone density distribution on the femorotibial articular surface of the tibia were examined both preoperatively and >1 year postoperatively using computed tomography osteoabsorptiometry. Quantitative analyses were conducted on the locations and percentages of the high-density areas (HDAs) on the articular surface. The mean time between surgery and the postoperative radiograph and computed tomography absorptiometry imaging was 13.6 months (range, 11-19 months). The mean length of clinical follow-up was 28.7 months (range, 14-62 months) after surgery.

RESULTS

The mean proportion of HDA in the lateral compartment relative to the total HDA (lateral ratio) was significantly greater in the preoperative OA group (58.8%) compared with the control group (41.1%) (P < .001). After MCW-DFVO, the mean lateral ratio in the OA group notably declined to 45.3% (P < .001). The lateral ratio exhibited a significant correlation with the hip-knee-ankle angle in both the control (r = 0.630; P = .011) and OA (r = 0.537; P = .047) groups. Moreover, the alteration in the lateral ratio after MCW-DFVO showed a significant relationship with changes in the hip-knee-ankle angle (r = 0.742; P = .002) and the mechanical lateral distal femoral angle (r = -0.752; P = .002). Within the lateral compartment, HDAs in the 3 lateral regions of the 4 lateral subregions diminished after MCW-DFVO, whereas in the medial compartment, HDAs in the 3 lateral subregions saw an increase.

CONCLUSION

The mean lateral ratio was significantly greater in the preoperative OA group compared with the control group. MCW-DFVO resulted in a redistribution of HDA from the lateral to the medial compartment of the proximal tibial articular surface. The extent of alignment correction after MCW-DFVO was closely linked to the shifts in HDA distribution, reflecting changes in stress distribution.