Open Wedge Distal Femoral Osteotomy: Accuracy of Correction and Patient Outcomes

Around-the-knee osteotomies part II: Surgical indications, techniques and outcomes - State of the art

Recent advances in surgical techniques and planning for knee-based osteotomies have led to improvements in addressing lower extremity malalignment. Part 1 of this review presented the biomechanical and clinical rationale of osteotomies, emphasizing the importance of osteotomies for restoring normal knee kinematics. In Part 2 of this review, indications, surgical technique and outcomes of osteotomies to correct coronal, sagittal and axial plane deformities will be examined. Traditional high tibial and distal femoral osteotomies will be discussed in addition to more recent advanced techniques including biplanar corrections and double-level osteotomies, as well as slope-correcting osteotomies. Patient-specific instrumentation and its use in more complex corrections will also be addressed.

Efficacy and Complications of Fixator-Assisted Correction with Internal Fixation in the Genu Valgum

Background and Purpose

Two basic methods for genu valgum correction are osteotomy and internal fixation or external fixator assited correction. External fixators have the advantage of stabilizing fragments before osteotomy allowing better control of fragments and preventing secondary displacements. The purpose of this study was to evaluate the efficacy and complications of fixator assisted correction for genu valgum and internal fixation, using the AO distal femur pediatric osteotomy plate.

Materials and Methods

Thirty-six limbs in 26 patients (age 10-16 years) underwent osteotomy in the distal femur at CORA. Open lateral wedge osteotomy was done; the desired position obtained was temporarily stabilized by connecting the pins with the AO external fixator and stabilized with 90 degrees AO distal femur pediatric locking plate and gap grafted with hydroxyapatite bone granules.

Results

Translation of distal fragment was required in 17 osteotomies (53.12%). Osteotomies united within 12 weeks; no non-union was observed. The range of motion was full in all patients. The mean tibiofemoral angle was corrected by 12 degrees and the mean mechanical LDFA was corrected to 87 degrees. There was no secondary deformity, either in the rotational or sagittal plane.

Conclusion

This method combines the modularity of external fixator and the advantages of internal fixation.

Distal Femoral Osteotomy for the Management of Coronal Deformity Following Total Knee Arthroplasty: A Report of 2 Cases

CASE

We present 2 cases demonstrating the management of coronal malalignment with an existing total knee arthroplasty using opening wedge distal femur osteotomy. The mechanical axis was corrected, and the primary total knee implants were maintained. Patients resumed full activity 3 to 4 months after surgery.

CONCLUSION

In certain cases, opening wedge distal femoral osteotomy is an option to correct coronal malalignment with an existing total knee arthroplasty without revising the implant.

Optimal Sequence of Corrective Surgeries for Concomitant Valgus Knee and Rigid Pes Planus Deformities: The Knee-First Approach

In patients requiring surgical correction of ipsilateral valgus knee and rigid pes planovalgus deformities, the optimal operative sequence is controversial. Growing evidence suggests these 2 deformities are related in etiology and interrelated in disease course. We present the case of a 72-year-old female with concomitant valgus knee and rigid pes planovalgus deformities successfully treated with total knee arthroplasty followed by triple arthrodesis and Achilles lengthening. Surgical correction of these deformities must be carefully planned between the operating surgeons to avoid over- or under-correction of alignment that could further impact gait. In contrast with the limited available literature, the authors recommend correction at the knee first and the foot and ankle second. Further prospective studies are needed to elucidate the best operative sequence in these patients.

Additional Plate Fixation of Hinge Fractures After Varisation Distal Femoral Osteotomies Provides Favorable Torsional Stability: A Biomechanical Study

BACKGROUND

Hinge fractures are considered risk factors for delayed or nonunion of the osteotomy gap in distal femoral osteotomies (DFOs). Limited evidence exists regarding the treatment of hinge fractures after DFO, which could improve stability and thus bone healing.

PURPOSE

To (1) examine the effect of hinge fractures on the biomechanical properties of the bone-implant construct, (2) evaluate the biomechanical advantages of an additional fixation of a hinge fracture, and (3) test the biomechanical properties of different types of varisation DFOs.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 32 fresh-frozen human distal femora equally underwent medial closing wedge DFO or lateral opening wedge DFO using a unilateral locking compression plate. The following conditions were serially tested: (1) preserved hinge; (2) hinge fracture along the osteotomy plane; (3) screw fixation of the hinge fracture; and (4) locking T-plate fixation of the hinge fracture. Using a servo-hydraulic materials testing machine, we subjected each construct to 15 cycles of axial compression (400 N; 20 N/s) and internal and external rotational loads (10 N·m; 0.5 N·m/s) to evaluate the stiffness. The axial and torsional hinge displacement was recorded using a 3-dimensional optical measuring system. Repeated-measures 1-way analysis of variance and post hoc Bonferroni correction were used for multiple comparisons. Statistical significance was set at P < .05.

RESULTS

Independent from the type of osteotomy, a fractured hinge significantly (P < .001) increased rotational displacement and reduced stiffness of the bone-implant construct, resulting in ≥1.92 mm increased displacement and ≥70% reduced stiffness in each rotational direction, while the axial stiffness remained unchanged. For both procedures, neither a screw nor a plate could restore intact rotational stiffness (P < .01), while only the plate was able to restore intact rotational displacement. However, the plate always performed better compared with the screw, with significantly higher and lower values for stiffness (+38% to +53%; P < .05) and displacement (-55% to -72%; P < .01), respectively, in ≥1 rotational direction. At the same time, the type of osteotomy did not significantly affect axial and torsional stability.

CONCLUSION

Hinge fractures after medial closing wedge DFO and lateral opening wedge DFO caused decreased bone-implant construct rotational stiffness and increased fracture-site displacement. In contrast, the axial stiffness remained unchanged in the cadaveric model.

CLINICAL RELEVANCE

When considering an osteosynthesis of a hinge fracture in a DFO, an additional plate fixation was the construct with the highest stiffness and least displacement, which could restore intact hinge rotational displacement.

Outcomes of Distal Femoral Osteotomy for Valgus Malalignment: A Systematic Review and Meta-analysis of Closing Wedge Versus Opening Wedge Techniques

BACKGROUND

Valgus knee deformity increases the risk for lateral articular chondral damage, contributing to earlier onset and accelerated progression of osteoarthritis. Distal femoral osteotomy (DFO) unloads the lateral joint compartment and can be performed using closing wedge (CW) or opening wedge (OW) techniques.

PURPOSE

To perform a systematic review and meta-analysis for patients with valgus knee deformity undergoing DFO to determine differences in patient-reported outcome measures (PROMs), complications, and survival rates, comparing CW versus OW DFO.

STUDY DESIGN

Systematic review, Level of evidence, 4.

METHODS

A literature review was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines utilizing PubMed, Cochrane Database, Ovid/MEDLINE, and Scopus. Inclusion criteria consisted of studies reporting outcomes in patients undergoing CW or OW DFO for the treatment of valgus knee deformities with symptomatic lateral compartment pathology with a minimum 2-year follow-up. PROMs and complications were analyzed using random-effects modeling to identify differences in outcomes as a function of surgical technique. Long-term survival data, defined as conversion to total knee arthroplasty, were analyzed using a multiple metaregression model as a function of individual study follow-up time points and surgical technique.

RESULTS

In total, we included 23 retrospective studies (n = 619 knees), of which 10 studies (n = 271 knees) reported outcomes after CW DFO and 13 studies (n = 348 knees) reported on OW DFO outcomes. Good to excellent clinical outcomes were reported in PROMs when compared with preoperative values with both techniques, while no significant differences between techniques were appreciated on functional Knee Society Scores and Tegner scores. No significant differences were appreciated in the incidence of complications reported in patients undergoing CW (20%) versus OW (33%) DFO (P = .432). Pain requiring hardware removal was the most commonly reported complication in both groups. The survival rate for CW DFO was 81.5% (mean follow-up, 8.8 ± 4.3 years) compared with 90.5% for OW DFO (mean follow-up, 4.5 ± 1.5 years). Multiple metaregression demonstrated that patient follow-up (P < .001) was significantly associated with knee survival, while surgical technique (P = .810) was not a predictor of clinical failure.

CONCLUSIONS

Both CW and OW DFO techniques were associated with good to excellent clinical outcomes with no significant differences in PROMs based on technique. Pain requiring hardware removal was the most common complication in both techniques, while long-term survivability was found to be a function of follow-up and not surgical technique. Technique selection should be based on shared patient-physician decision making with an emphasis on surgeon preference and technique familiarity.

Distal femur varus-producing osteotomy: An updated review of patellofemoral implications and clinical outcomes

Background: Recent evidence seems to suggest the effectiveness of distal femur varus osteotomy in the management of patellofemoral instability in the setting of genu valgum. However, literature on this subject remains scarce and consists mostly of small case series. Hypothesis: This study aims to systematically review the literature on varus-producing distal femur osteotomy and critically analyze its implications on patellofemoral kinematics and stability. Results: The statistical analysis revealed that this surgery is able to restore a mechanical angle (mean hip–knee–ankle (HKA): 0.22°) and to improve the main clinical outcomes (Kujala score, Knee injury and Osteoarthritis Outcome Score, visual analog scale) after a mean follow up of 2.5 years. An objective of the present review was to investigate the mechanical implications of femoral osteotomy on the patellofemoral biomechanics. Indeed, the statistical analysis demonstrated changes after surgery in the main patella-femoral radiological angles (modified Insall–Salvati index, Caton–Deschamps index, Blackburne–Peel index). Interestingly the overcorrection of the mechanical axis (HKA), resulting in varus, had similar outcomes compared to studies that obtained a mechanical axis. Level of Evidence: Level II study.

Opening wedge high tibial osteotomy for medial compartment knee osteoarthritis: Planning and improving outcomes: Case series and literature review

Background

Opening wedge high tibial osteotomy (OWHTO) is a safe surgical procedure to treat medial compartmental osteoarthritis caused by a varus deformity. Over-correction of this varus deformity can lead to lateral compartment over-loading. In our study, we planned our correction by using the mechanical axis deviation (MAD).

Purpose

The purpose of this study is to evaluate the clinical and radiological results of OWHTO based on planning using the MAD measurements.

Study Design

Retrospective Case Series.

Methods

14 patients with Kellgren- Lawrence classification (KL) grade 3 or above underwent OWHTO, with plans to have the mechanical axis pass through 5-15 mm lateral to the center of the tibial plateau. Pre-operative and post-operative radiographic measurements were made and compared using the student t-test. SF-36 scores were obtained for clinical performance.

Results

Our patients experienced MAD from 25.9 mm medial to the center of the tibial plateau pre-operatively to 12.7 mm lateral to the center of the plateau post-operatively. The mean change in MAD was 38.7 mm (p < 0.0001). The accuracy of our correction compared to the planned MAD was 98.3%. The mechanical axis angle shifted from 7.35° of varus to 3.5° of valgus (p < 0.0001). All patients had post-operative alignments of 1-6° of valgus, with 11 of out the 14 patients with alignments less than 5° of valgus, preventing over-loading of the lateral compartment.

Conclusion

Using MAD measurements is an accurate planning method for OWHTO that corrects varus deformity without over-loading the lateral compartment, and leads to improved clinical outcomes.

[Research progress of osteotomy around knee in the treatment of valgus knee osteoarthritis]

OBJECTIVE

To review the research progress of surgical methods of osteotomy around the knee in the treatment of valgus knee osteoarthritis.

METHODS

The relevant literature on the surgical treatment of valgus knee osteoarthritis at home and abroad in recent years was reviewed, and the advantages, disadvantages, and effectiveness of different surgical methods of osteotomy around the knee were summarized.

RESULTS

For young and active patients with symptomatic valgus knee osteoarthritis, osteotomy around the knee is a safe and reliable treatment option. At present, the main surgical methods include medial closing wedge distal femoral osteotomy, lateral opening wedge distal femoral osteotomy, medial closing wedge high tibial osteotomy, and lateral opening wedge high tibial osteotomy. The indications, advantages, and disadvantages of different osteotomies are different, and the selection of appropriate surgical method is the key to achieve good effectiveness.

CONCLUSION

There are many osteotomies in the treatment of valgus knee osteoarthritis. In order to achieve good results, improve survival rate, and reduce postoperative complications, the most reasonable surgical strategy needs to be developed according to different situations.

Comparison and Validation of Preoperative Planning Techniques for Distal Femoral Osteotomies and Proximal Tibial Osteotomies

Preoperative planning is important for accurate intraoperative execution in many surgical fields. Planning for distal femoral osteotomies (DFOs) and proximal tibial osteotomies (PTOs) consists of choosing the level of the osteotomy, measuring the angle of the osteotomy based on hip-knee-ankle alignment, and choosing a proper osteotomy wedge size. Medical imaging IT solutions company Sectra has implemented a new osteotomy tool in their radiographic system that is simpler than the accepted standard of modified center of rotation of angulation (mCORA) technique, yet unvalidated. In this study, we aim to compare the Sectra osteotomy tool versus the mCORA technique to measure the osteotomy angles as well as wedge sizes in both DFOs and PTOs to validate this new tool.We enrolled n = 30 consecutive patients with DFOs and n = 30 PTOs from the last year. The Pearson correlation coefficient (PCC) along with descriptive statistics was used to evaluate for similarity between the two techniques. We also compared interobserver and intraobserver reliability using intraclass correlation coefficients (ICC).The PCC for osteotomy angles in DFOs and PTOs were both 0.998 (p < 0.001 for both). For wedge sizes, the PCC in DFOs was 0.993 and 0.980 in PTOs (p < 0.001 for both). ICCs were high for both interobserver measurements in osteotomy angles and wedge sizes (range: 0.989-0.999) as well as intraobserver measurements (0.994-0.999).The Sectra osteotomy tool is a validated tool for preoperative measurements of DFOs and PTOs. It is reliable and simpler than the current practice of the mCORA technique. We suggest future studies to analyze this Sectra osteotomy tool in other settings as to incorporate it into widespread clinical use.

CT based PSI blocks for osteotomies around the knee provide accurate results when intraoperative imaging is used

Purpose

Correction osteotomies around the knee are common methods for the treatment of varus or valgus malalignment of the lower extremity. In recent years, patient specific instrumentation (PSI) guides were introduced in order to enhance the accuracy of these procedures. The purpose of this study was to determine the accuracy of CT based PSI guides for correction osteotomies around the knee of low volume osteotomy surgeons and to evaluate if CT based PSI blocks deliver a high degree of accuracy without using intraoperative fluoroscopy.

Methods

Two study arms with CT based PSI cutting blocks for osteotomies around the knee were conducted. Part one: A retrospective analysis of 19 osteotomies was made in order to evaluate the accuracy in the hands of a low volume surgeon on long-leg radiographs. Part two: A cadaveric study with 8 knees was performed for the purpose of analyzing the accuracy without using intraoperative fluoroscopy on pre- and postoperative CT scans. Hip-Knee-Ankle angle (HKA), lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) were analyzed. The mean absolute delta (∂) between the planned and postoperative parameters were calculated. The accuracy of both study arms were compared.

Results

Part one: The mean MPTA ∂, LDFA ∂ and HKA ∂ was 0.9°, 1.9° and 1.5°, respectively. Part two: The mean MPTA ∂ and LDFA ∂ was 3.5° and 2.2°, respectively. The mean ∂ of MPTA is significantly different between clinical patients with fluoroscopic control and cadaveric specimens without fluoroscopic control (P < 0.001). All surgeries were performed without complications such as a hinge fracture.

Conclusion

The clinical use of PSI guides for osteotomies around the knee in the hands of low volume surgeons is a safe procedure. The PSI guides deliver a reliable accuracy under fluoroscopic control whereas their non-use of intraoperative fluoroscopy leads to a lack of accuracy. The use of fluoroscopic control during PSI guided correction osteotomies is highly recommended.

Level of evidence

IV – Retrospective and experimental Study

Proximal tibial osteotomy for genu varum: Radiological evaluation of deformity correction with a plate vs external fixator

BACKGROUND

High tibial osteotomy (HTO) is a well-known procedure for the correction of knee varus. The purpose of this study was to compare the radiological results and accuracy of deformity correction performed using two different techniques: acute opening wedge correction using a plate and gradual correction with a monolateral external fixator.

AIM

To compare of the radiological results of two different techniques: acute opening wedge correction (a plate and screw) and gradual correction (external fixator).

METHODS

A total of 43 patients with plates and 36 patients with external fixators were included. All patients had moderate uniplanar varus deformities. We measured radiographic parameters, including the mechanical axis deviation (MAD), medial proximal tibial angle (MPTA), Caton-Deschamps Index (CDI), posterior proximal tibial angle, and joint line obliquity angle (JLOA). The accuracy of MAD correction was calculated based on a correction goal of neutral or overcorrection for medial compartment arthritis.

RESULTS

Demographics including age, body mass index, sex, and preoperative deformities were similar between the groups. The MAD significantly improved from 23.6 mm medial to the midline (SD = 8.2 mm) to 6.9 mm lateral to the midline (SD = 5.4 mm) (P < 0.001). The accuracy of MAD correction did not differ between the groups and was 96.1% (SD = 8.1%) in the plate group and 98.2% (SD = 5.2%) in the external fixator group (P = 0.18). The MPTA significantly improved from 83.9° (SD = 2.9°) to 90.9° (SD = 3.3°) (P < 0.001), and the change was similar between the groups. Differences were noted in patella height, with a CDI change of -19.2% (SD = 13.7%) and 3.1% (SD = 8.0%) for the plate and external fixator groups, respectively (P < 0.001). The change in JLOA was 1.6 degrees (SD = 1.1 degrees) and 0.9 degrees (SD = 0.9 degrees) for the plate and external fixator groups, respectively (P = 0.04).

CONCLUSION

Reliable correction of moderate varus alignment was achieved with both the acute opening wedge technique with a plate and the gradual monolateral external fixator technique. The patellar height decreased with the open wedge plate technique. Joint line obliquity decreased to a greater degree with the open wedge plate technique, perhaps as a result of medial collateral ligament release. The appropriate technique should be selected based on surgeon and patient preferences; however, external fixation may be a better choice when the preservation of patellar height is deemed important.

Ten-year survival rate of 89% after distal femoral osteotomy surgery for lateral compartment osteoarthritis of the knee

PURPOSE

The purpose of this study was to assess the accuracy, safety, and survival of distal femoral osteotomy (DFO) surgery for lateral compartment OA of the knee.

METHODS

A retrospective cohort study was conducted at a single UK centre, using prospectively collected data over an 8-year period (2009-2017). All patients had pre-operative radiographic analysis and digital planning of their deformity correction in addition to post-operative analysis of the achieved correction and yearly face-to-face follow-up. Complications (defined as an undesirable medical or surgical event as a direct result of the operation), reoperations, and failure (defined as conversion to arthroplasty or revision) were recorded.

RESULTS

From a total of 83 patients, 81 patients undergoing 86 primary DFOs were included in this study, with a mean follow-up of 99 months (SD 27 months). The mean pre-operative percentage Mikulicz point was 78.7% (SD 19.1%) and post-operative 35.9% (SD 14.8%). The mean accuracy of correction (intended correction - achieved correction) was an 8.2% overcorrection (SD 13.7%). The complication rate was 4.7%. Using Kaplan-Meier analysis, the mean survival was 113 months (95% CI 106-120) with the probability of surviving 10 years 89%.

CONCLUSION

DFO for valgus alignment and lateral compartment arthritis is associated with low complications, long-term joint preservation, and the prevention of arthroplasty surgery. However, the accuracy of correction still requires improvement in intra-operative technique.

LEVEL OF EVIDENCE

IV.

A hinge position distal to the adductor tubercle minimizes the risk of hinge fractures in lateral open wedge distal femoral osteotomy

PURPOSE

To evaluate the incidence and morphology of medial cortical hinge fractures in lateral open wedge distal femoral osteotomy (LOW-DFO) and to determine a safe zone for the position of the osteotomy hinge to minimize the risk of hinge fractures.

METHODS

Consecutive patients who underwent LOW-DFO for symptomatic valgus malalignment were screened for eligibility for this retrospective observational cohort study. Demographical and surgical data were collected. The incidence and morphology of medial cortical hinge fractures were evaluated on standard postoperative anterior-posterior knee radiographs. Comprehensive measurements evaluating the osteotomy gap and the position of the osteotomy hinge were taken. Additionally, each osteotomy hinge was assigned to a corresponding sector of a proposed five-sector grid of the distal medial femur.

RESULTS

A total of 100 patients (60% female) with a mean age of 31 ± 13 years were included. The overall incidence of medial cortical hinge fractures was 46% and three distinct fracture types were identified. The most frequently observed fracture type was extension of the osteotomy gap (76%), followed by a proximal (20%) and distal (4%) course of the fracture line in relation to the hinge. Group comparison (hinge fracture vs. no hinge fracture) showed statistically significant higher values for the height of the osteotomy gap (p = 0.001), the wedge angle (p = 0.036), and the vertical distance between the hinge and the proximal margin of the adductor tubercle (AT; p = 0.002) in the hinge fracture group. Furthermore, a significantly lower horizontal distance between the hinge and the medial cortical bone (p = 0.036) was observed in the hinge fracture group. A statistically significant higher incidence of medial cortical hinge fractures was observed when the position of the osteotomy hinge was proximal compared to distal to the proximal margin of the AT (53% vs. 27%; p = 0.023).

CONCLUSION

Medial cortical hinge fractures in LOW-DFO are a common finding with three distinct fracture types. To minimize the risk of medial cortical hinge fractures, it is recommended to aim for a position of the osteotomy hinge at the level of or distal to the proximal margin of the adductor tubercle.

LEVEL OF EVIDENCE

Prognostic study; Level III.

Resultados a longo prazo de osteotomia varizante femoral distal (OVFD) com cunha de abertura lateral para artrose do compartimento lateral do joelho utilizando navegação computadorizada

Objective  The primary aim of the present study was to evaluate the long-term outcomes including survivorship of computer navigated distal femoral lateral opening wedge osteotomy (DFLOWO). The secondary aim was to identify the potential factors that may influence its survivorship.

Methods  A retrospective analysis of prospectively collected data for patients with lateral compartment arthritis who underwent navigated DFLOWO from December 2006 to November 2012 was performed. The International Knee Documentation Committee (IKDC) and Knee Injury and Osteoarthritis Outcome Score (KOOS) scores were analyzed for outcome measures. Conversion to arthroplasty during the follow-up was the end point.

Results  A total of 19 DFLOWOs were performed in 17 patients with a mean age of 46.6 ± 6.5 years formed the study cohort. The coronal alignment was corrected from a mean of 7.1° (2–11°) valgus to a mean of 2.1° (0.5°–3°) varus. The IKDC scores improved from mean of 39 preoperatively to 53 at the mean long-term follow-up of 9.1 years. The mean KOOS scores at the long-term follow-up were pain 71, symptoms 56, activities of daily living 82, sports and recreation 59, quality of life 43. Survivorship of the DFLOWO was 78.9% at a follow-up of 9.1 years. Presence of ≥ grade 2 according to the International Cartilage Repair Society (ICRS) cartilage degeneration in the medial compartment of the knee and >7° preoperative valgus deformity were strongly correlated with conversion to total knee arthroplasty (TKA) at the long-term follow-up ( r  = 0.66).

Conclusions  Computer navigated DFLOWO has satisfactory clinical outcomes and 79% survivorship in long-term follow-up. Presence of more than ICRS ≥ grade 2 degenerative changes in the medial compartment of knee with > 7° preoperative valgus deformity negatively affects the survivorship of DFLOWO in the long-term follow-up.

Opening-wedge osteotomies of the distal femur: minor advantages for a biplanar compared to a uniplanar technique

PURPOSE

Valgus malalignment of the distal femur may be treated with corrective osteotomy. The purpose of this study was to compare the primary stability of a lateral opening-wedge osteotomy (LOWO) using a uniplanar compared to a biplanar technique. A study was carried out to test both surgeries, with both an intact medial cortex and with a deliberate attached cut of the medial cortex simulating a fracture. The primary hypothesis was that the biplanar technique provides higher axial and torsional stiffness. It was further hypothesized that the mechanical superiority of the biplanar technique would not be affected in the case of breakage of the far medial cortex.

METHODS

A LOWO was performed in ten synthetic femora (#3406 left large Femur, 4th Generation, Sawbones, Malmö, Sweden) using a lateral angle stable locking plate (NCB© Distal Femur Plate, Zimmer Biomet, Warsaw, USA). A uniplanar osteotomy was performed in five femora, and a biplanar osteotomy was performed in five femora. The femora were tested for axial and torsional loads using a servo-hydraulic testing machine (Instron 8874, Instron Structural Testing GmbH, High Wycombe, UK).

RESULTS

Axial stiffness decreased significantly (p = 0.001) in both groups (20% in the uniplanar group and 28 % in the biplanar group) by cutting the medial cortex. The type of osteotomy had no significant effect. A slightly lower but not statistically significant axial stiffness was seen in the biplanar group both for intact and broken medial cortices. Internal torsional stiffness dropped by more than 30% for the uniplanar group and almost 24% for the biplanar group when the cortex was cut (p < 0.001). No significant change concerning internal torsional stiffness was found between the two groups. External torsional stiffness decreased by 32% for the uniplanar group and 4% for the biplanar group after the cortical cut (p = 0.029). No significant change concerning external torsional stiffness was found between the groups, but the biplanar group showed a tendency towards higher values of external torsional stiffness.

CONCLUSIONS

The axial and torsional stiffness of the implant-bone construct were not significantly affected by the type of osteotomy performed. Biplanar osteotomy tended to increase external torsional stiffness. In cases of fracture of the medial cortex, biplanar osteotomy significantly reduced the external rotation at the osteotomy and showed a significantly increased external torsional stiffness.

Lateral Opening Wedge Distal Femoral Osteotomy for Lateral Compartment Arthrosis/Overload

Distal femoral osteotomy (DFO) is a valid option for the treatment of young and active patients with lateral compartment osteoarthritis/overload and valgus malalignment. DFOs can be performed with a closing wedge or opening wedge technique. Lateral opening wedge DFO is usually preferred for smaller corrections, whereas medial closing wedge for larger corrections and in patients with high risk of nonunion. This article describes the relevant aspects regarding lateral opening wedge DFO, including patient selection, preoperative planning, surgical technique, results, and complications.

Medial Open-wedge Osteotomy with Double-plate Fixation for Varus Malunion of the Distal Femur

Objective

To present our clinical experience of treating varus malunion of the distal femur through a medial open‐wedge osteotomy with double‐plate fixation.

Methods

A prospective cohort study was performed. From January 2005 to February 2015, 15 consecutive patients with varus malunion following distal femur fractures were surgically treated at a single level I trauma center. The coronal and sagittal deformity were corrected by a medial open‐wedge osteotomy of the distal femur. A medial buttress plate was used to maintain the realignment. A lateral locking plate was additionally used as a protection plate. The mean age of patients at the time of the surgery was 35.5 years (range, 22–58 years). The radiographical evaluation included the mechanical femorotibial angle, the mechanical lateral distal femoral angle, the anatomic posterior distal femoral angle, and the leg length discrepancy. Clinical outcome evaluation consisted of the range of motion (ROM) and Hospital for Special Surgery (HSS) score.

Results

Mean follow‐up was 7.4 years (range, 4–11.5 years). Varus and flexion malalignment and limb discrepancy were adequately corrected in all patients. The mechanical femorotibial angle, the mechanical lateral distal femoral angle, and the anatomic posterior distal femoral angle were restored from 17.5° (range, 13°–25°) to 2.3° (range, − 2°–7°), 102.3° (range, 95°–112°) to 85.2° (range, 81°–92°), and 77.1° (range, 65°–87°) to 82.7° (range, 76°–88°), respectively. The leg length discrepancy was diminished from 3.4 cm (range, 2.4–4.5 cm) to 0.8 cm (range, 0–1.7 cm). The average bone healing time was 4.1 months (range, 2.5–6 months). The average ROM of the affected knees at 24‐month follow‐up was 3.4°–112.55°. The score of HSS at 4‐years follow‐up was 76.1 (range, 64–88). No internal fixation failure or secondary operation was noted until the last follow‐up.

Conclusion

Medial open‐wedge osteotomy can adequately correct the posttraumatic varus malunion of the distal femur. With fixation of the double plate, non‐displaced bone healing and good functional outcome are expected.

Distal femoral varus osteotomy: results of the lateral open-wedge technique without bone grafting

Background

The lateral opening wedge distal femoral osteotomy (LOWDFO) to reconstruct knee alignment in patients with genu valgum originating in the distal femur has gained importance within the last years.

Purpose

To analyze clinical and radiographic outcome of patients treated with LOWDFO with respect to bone healing without grafting and patient age.

Material and methods

Twenty-two consecutive patients with genu valgum corrected with 23 LOWDFOs using a Tomofix-locking plate were retrospectively analyzed (mean age 23.7 years). Clinical evaluation was based on pre- and post-operative KOOS scores. A pre- and post-operative radiographic assessment, including MAD, mLDFA, LLD, bone healing, and patella parameters, was performed. Differences between subgroups (age, bone grafting) were analyzed.

Results

The restoration of MAD and mLDFA resulted in significantly improved post-operative KOOS₅ scores in younger and older patients (p = 0.001). Bone healing without bone grafting was reliable in all patients. The leg length was significantly increased post-operatively (p = 0.001). The Blackburne-Peel ratio was significantly reduced to more normal values post-operatively (p < 0.001).

Conclusion

LOWDFO without bone grafting is a reliable procedure representing a promising treatment option particularly in young patients with genu valgum. Besides correction of the MAD, a significant leg length increase and additional patella stability can be expected.

SPECT/CT in the Postoperative Painful Knee

This review summarizes the role of SPECT/CT in patients with a painful postoperative knee and describes typical diagnostic criteria in these patients. Pain after knee surgery is common and is influenced by the underlying pathology, the type of surgery, and the patient. Knee joint-preserving surgery includes osteotomy, ligament reconstruction, meniscus surgery, and cartilage repair procedures, often used in combination. Knee arthroplasty procedures consist of unicondylar, patellofemoral, and primary or revision total knee prosthesis. In patients with pain after knee joint-preserving surgery, MRI remains the reference standard. After ligament reconstruction, CT can evaluate postoperative tunnel positioning, and bone SPECT/CT can contribute by assessing overloading or biodegradation problems. After meniscal or cartilage surgery, SPECT/CT can be particularly helpful to identify compartment overloading or nonhealing chondral or osteochondral lesions as cause of pain. SPECT/CT arthrography can assess cartilage damage at an early stage due to altered biomechanical forces. After corrective osteotomy of the knee, SPECT/CT can reveal complications such as overloading, nonunion, or patellofemoral problems. After arthroplasty, conventional radiographs lack both sensitivity to detect aseptic loosening and specificity in differentiating aseptic from infectious loosening. Secondly, hardware-induced artifacts still hamper CT and MRI, despite improving and increasingly available metal artifact reduction techniques. Bone scintigraphy is a proven useful adjunct to conventional radiography and MRI to reveal the pain generator and is less hampered by artifacts from metallic implants compared with CT and MRI. Nevertheless, the optimal imaging strategy in evaluating complications after knee arthroplasty is still a matter of debate. Although the evidence of the use of BS SPECT/CT is still limited, it is growing steadily. In particular, recent data on specific uptake patterns in tibial and femoral zones after total knee arthroplasty and the impact of integrating biomechanics into the assessment of SPECT/CT appear promising, but more research is needed.