Medialization of the mechanical axis of the tibia is related to lateralization of the tibial tuberosity in knee osteoarthritis

PurposeTo determine whether medialization of the proximal tibia due to a varus deformity is related to lateralization of the tibial tuberosity in varus knee osteoarthritis (OA).MethodsA total of 120 knees that underwent osteotomies around the knee for varus knee OA were enrolled. Mechanical medial proximal tibial angle (mMPTA) was measured on radiographs. The angle between the mechanical and anatomical axes of the tibia (angle MA) and the distance between the centre of the tibial plateau and the anatomical axis (distance MA) were measured in the coronal plane on computed tomography images. The tibial tuberosity–posterior cruciate ligament (TT-PCL) distance, the distance between the midpoint of the tibial tuberosity and the centre of the tibial plateau (TT-centre distance), and the angle between the line through the midpoint of the tibial tuberosity and the centre of the tibial plateau and the anteroposterior axis (TT-centre angle) were measured in the axial plane. The correlations of these parameters were evaluated.ResultsmMPTA correlated negatively with angle MA (r = −0.37, P < 0.01) and distance MA (r = −0.55, P < 0.01). Angle MA and distance MA correlated with TT-PCL distance (r = 0.39, P < 0.01, r = 0.42, P < 0.01), TT-centre distance (r = 0.35, P < 0.01, r = 0.38, P < 0.01) and TT-centre angle (r = 0.36, P < 0.01, r = 0.36, P < 0.01).ConclusionsMedialization of the proximal tibia due to a varus deformity may induce lateralization of the tibial tuberosity.     

How to fix a tibial tubercle osteotomy with distalisation: A finite element analysis

BackgroundAntero-medialisation osteotomy combined with a distalisation procedure may require a more stable fixation as the osteotomy fragment loses both proximal and distal support. This finite element analysis aimed to compare the mechanical behaviour of different fixation techniques in tibial tubercle antero-medialisation osteotomy combined with distalisation procedure.MethodsTibial tubercle osteotomy combined with distalisation was modelled based on computerised tomography data, which were acquired from a patient with patellar instability requiring this procedure. Six different fixation configurations with two 3.5-mm cortical screws (1), two 4.5-mm cortical screws (2), three 3.5-mm cortical screws (3), three 4.5-mm cortical screws (4), three 3.5-mm screws with 1/3 tubular plate (5), and four 3.5-mm screws with 1/3 tubular plate (6) were created. A total of 1654 N of force was applied to the patellar tendon footprint on the tibial tubercle. Sliding, gap formation, and total deformation between the osteotomy components were analyzed.ResultsMaximum sliding (0.660 mm), gap formation (0.661 mm), and displacement (1.267 mm) were seen with two 3.5-mm screw fixation, followed by two 4.5-mm screws, three 3.5-mm screws, and three 4.5-mm screws, respectively, in the screw-only group. Overall, the minimum displacement was observed with the four 3.5-mm screws with 1/3 tubular plate fixation model.ConclusionsPlate fixation might be recommended for tibial tubercle antero-medialisation osteotomy combined with distalisation procedure because it might allow early active range of motion exercises and weight-bearing.     

The degree of correction in open-wedge high tibial osteotomy compromises bone healing: A consecutive review of 101 cases

BackgroundThe bone healing in open-wedge high tibial osteotomy (OWHTO) proceeds gradually by a filling of the osteotomy gap. This can comprise several risk factors.MethodsA retrospective study analysed the clinical and radiological course of 101 consecutive OWHTOs in 96 patients. The following risk factors were considered: age, body mass index, tobacco consumption, amount of tobacco consumption, severity of comorbidities, infection of the surgical area, occurrence of a lateral hinge fracture and the degree of correction. The bone healing was evaluated by using the modified Radiographic Union Score for Tibial fractures (RUST).ResultsA disturbance in bone healing was observed in 16 of the 101 osteotomies. Binary logistic regression analysis showed a correlation between the angle of the opening wedge and the development of a disturbance in bone healing (P = 0.002). The odds ratio indicated an increase in the risk of a disturbance in bone healing of 56% with each additional degree of correction. For the risk factor ‘age’ a statistical trend was recognizable (P = 0.077) with the risk of a disturbance in bone healing in higher age.ConclusionLateral hinge fractures seem not to have a detrimental effect on the filling of the osteotomy gap. An increase in the opening wedge bears the risk of a disturbance in bone healing.     

Faster bone union progression and less sclerosis at the osteotomy margin after medial opening-wedge high tibial osteotomy using highly porous β-tricalcium phosphate granules versus allogeneic bone chips: A matched case–control study

BackgroundThis study compared bone union progression using highly porous (80% porosity) β-tricalcium phosphate (β-TCP) granules or allogeneic bone chips in the gap created by medial opening-wedge high tibial osteotomy (MOWHTO).MethodsThe study population consisted of 54 patients who received MOWHTO with locking plate fixation: 27 patients using highly porous β-TCP granules, and 27 age- and sex-matched patients using allogeneic bone chips. Bone union progression was evaluated 1, 3, 6, and 12 months postoperatively. The presence of radiographic sclerosis at the osteotomy margin was also assessed.ResultsAmong all patients, the highest degree of bone union observed 12 months postoperatively was grade 4. As postoperative time passed, bone union progression of highly porous β-TCP granules increased linearly and was statistically significant compared with that of cancellous allogeneic bone chips (P = 0.014). The presence of radiographic sclerosis at the osteotomy margin was significantly less common in the β-TCP group than in the allograft group (P = 0.003) and was the strongest predictor of delayed progress of bone union (odds ratio = 6.16, P = 0.006).ConclusionsPatients who underwent MOWHTO using highly porous β-TCP granules had faster new bone remodeling, less radiographic sclerosis at the osteotomy margin, and no inferior clinical outcome compared with allogeneic bone chips, as determined at the 1-year follow up. The presence of radiographic sclerosis at the osteotomy margin in patients undergoing MOWHTO using allogeneic bone or synthetic bone substitute may indicate delayed progress of bone union.     

High tibial derotation osteotomy for distal extensor mechanism alignment in patients with squinting patella due to increased external tibial torsion

BackgroundThe patellofemoral joint is often affected by torsional disorders of the lower limb, causing pain, instability and knee degeneration. The aims of this study were to determine functional outcomes of patients who underwent a high tibial derotation osteotomy (HTDO) for symptomatic squinting patella due to increased external tibial torsion. Moreover, factors associated with inferior clinical outcomes were investigated.MethodsPatients with symptomatic squinting patella, increased external tibial torsion (>30°) treated with this technique, and with 2 years of follow up were included. Fulkerson and Kujala patellofemoral joint scores were assessed. Age, body mass index, history of prior surgery, increased femoral anteversion, association of lateral retinaculum release and patellar cartilage lesions were analysed.ResultsSixty HTDOs were included in this retrospective study with an average of 66 months of follow up. The mean Kujala score improved from 47.5 preoperatively to 93 postoperatively. The mean Fulkerson score improved from 40.6 to 91.6. Kujala subscores for pain improved from 8.6 to 30.4, for instability improved from 6.4 to 17.9, and their ability to climb stairs increased from 6.9 to 17.9 (all P < 0.0001). Multivariate logistic regression model identified that patient age (P < 0.005) and advanced chondral damage (P < 0.001) were the dominant factors predicting inferior clinical outcomes using Kujala’s score.ConclusionHTDO provided good results regarding the pain symptoms, instability and the ability to climb stairs. Advanced chondral damage and advanced age had negative effects on outcomes.     

Open wedge high tibial osteotomy using three-dimensional printed models: Experimental analysis using porcine bone

Background

The purpose of this study was to evaluate the usefulness of three-dimensional (3D) printed models for open wedge high tibial osteotomy (HTO) in porcine bone.

Analysis of the relationship between the morphology of the proximal tibiofibular joint and lateral hinge fracture in open wedge high tibial osteotomy

BackgroundOne of the complications of open wedge high tibial osteotomy is lateral hinge fracture, which causes delayed bone healing. In this study, we focused on the morphology of the proximal tibiofibular joint to clarify the influence of this morphology on the occurrence of lateral hinge fracture in open wedge high tibial osteotomy.MethodsThe proximal tibiofibular joint of 58 knees in 55 patients who underwent open wedge high tibial osteotomy was classified as either horizontal or oblique, depending on the morphology of the fibular head. Lateral hinge fracture of Takeuchi classification type II or III was defined as unstable lateral hinge fracture. We analyzed whether patient background and bone morphological factors, including the morphology of the proximal tibiofibular joint, were associated with the occurrence of unstable lateral hinge fracture.ResultsThe horizontal and oblique types were found in 34 and 24 knees, respectively. There was no difference in the percentage of hinge points within the safe zone between the horizontal and oblique types; however, there was a significant difference in the unstable lateral hinge fracture incidence between the two groups. Unstable lateral hinge fracture occurred in seven knees, mostly in patients with an oblique proximal tibiofibular joint. The factors associated with the occurrence of unstable lateral hinge fracture were analyzed using logistic regression analysis; the fibular head of the oblique type was a significant factor.ConclusionOpen wedge high tibial osteotomy for oblique-type proximal tibiofibular joints may be more likely to cause unstable lateral hinge fracture than the horizontal type.     

In vitro stability of open wedge high tibial osteotomy with synthetic bone graft

It has been predicted that significant stress will be applied to the plate and lateral cortical hinge of an osteotomy site when early full weight bearing is commenced after an open wedge high tibial osteotomy. We hypothesized that the stress concentration on the plate or at the lateral cortical hinge would be reduced by inserting bone substitutes into the osteotomy gap. Two different types of tibia model were investigated: Group A, fixation with TomoFix with the osteotomy site left as an open space; and Group B, two β-TCP wedges are inserted into osteotomy site and fixed with TomoFix. Stress at five points was measured using strain gauges. Specimens were mounted onto a testing machine with an FTA (femoro-tibial angle) of 170°. Cyclic load tests and an ultimate load test were then performed. The mean stress on the plate was measured at 15.5 ± 1.8 Mpa in Group A. On the other hand, this value in Group B was only 9.52 ± 2.1 Mpa and this was a significant difference (P < 0.01). The mean stress on the lateral hinge in Groups A and B was 3.31 ± 0.5 and 2.49 ± 0.2, respectively which was also a significant difference (P < 0.05). The mean maximum breaking load in Group A was 2500 ± 280 N and in Group B 4270 ± 420 N which was a significant difference (P < 0.01). Hence, for OWHTO procedures, the use of β-TCP wedges and TomoFix is thus likely to improve the initial axial and possibly rotational stability at the osteotomy site in comparison with methods that leave the osteotomy gap open.     

Midterm follow-up results of two different types of implants in opening wedge high tibia osteotomy

BackgroundThis retrospective study investigated the midterm results of medial opening wedge high tibia osteotomy, with a monoplanar or a biplanar osteotomy using two types of implant system.MethodsOsteotomies were performed on 241 knees (231 patients). The mean follow-up period was 6.0 years (SD 3.0, range 0.2–12.8 years). Two types of implant system were used, a precountered non-locking plate (PP) (n = 74) and a precountered locking plate (LP) (n = 167). A Kaplan-Meier cumulative survival curve and a Cox regression model were used to analyse and revise survival and risk factors.ResultsCumulative survival estimates for LP were 80% at 5 years, and 64% at 10 years (SE = 0.4, CI 95%: 9.0–10.5), and for PP, they were 68% at 5 years and 49% at 10 years (SE = 0.5, CI: 95% 6.3–8.2) (p = 0.024). The revision rate was 26% (44/167) for the LP group, and 47% (35/74) for the PP group (p = 0.001). Reoperations on LP osteotomies occurred for the tibial monoplanar cut and biplanar cut groups, in 19/52 (37%) and 25/167 (16%) osteotomies, respectively (p = 0.04). Our Cox regression model showed that PP had a higher risks (RR = 1.7; CI: 95% 1.1–2.6) of revision, when compared with LP (p = 0.026).ConclusionsThe risk of revision for any reason and that of early conversion to total knee arthroplasty (TKA) after high tibia osteotomy were significantly increased for PP, when compared with LP.     

Cartilage repair examined by second-look arthroscopy following double-level osteotomy performed for osteoarthritic knees with severe varus deformity

BackgroundThe purpose of this study was to examine the status of cartilage repair by second-look arthroscopy following double-level osteotomy (DLO) performed for osteoarthritic knees with severe varus deformity.MethodsForty-seven consecutive knees in 33 patients who underwent DLO were included in the study. The surgical technique used was a minimally invasive DLO procedure combining lateral closed-wedge distal femoral and medial open-wedge high tibial osteotomies. In the second-look arthroscopic evaluation, the following grading system proposed by Koshino was adopted: Stage A, no repair; stage B, pink fibrous tissue with or without partial coverage with white fibrocartilage; and stage C, total coverage with cartilage. The findings corresponding to stage B or C were considered as repaired. Arthroscopic assessment was performed for each compartment. Clinical outcomes were evaluated using the validated outcome measures.ResultsThe mean age at surgery was 62.8 ± 6.2 years (range: 45–75 years), and the mean time period from DLO to second-look arthroscopy was 17.1 ± 5.0 months (range: 12–33 months). Cartilage repair to some extent was identified in over 90% of the medial femoral and tibial condyles, and 12.8% of the patellar facet. As for clinical scores, both Knee Injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee Subjective Knee Form (IKDC) subjective scores significantly improved after surgery (P < 0.01).ConclusionsEvaluation of the present study subjects showed that DLO could induce cartilage repair in the majority of the affected femoral and tibial articular surfaces with significant clinical improvement. In the patellar facet, however, cartilage repair could be identified in only 12.8% of cases.     

Coronal subluxation of the proximal tibia relative to the distal femur after opening wedge high tibial osteotomy

Background

The coronal subluxation of the proximal tibia relative to the distal femur is a common radiological finding in patients with knee osteoarthritis. The purpose was to evaluate whether the coronal subluxation was corrected after opening wedge high tibial osteotomy (OWHTO), and whether this subluxation was one cause of inconsistency between the actual and predicted alignments (correction loss).

Perioperative duloxetine administration reduces pain after high tibial osteotomy and non-steroidal anti-inflammatory administration: A prospective,controlled study

BackgroundPostoperative pain management is essential for patient satisfaction; however, no reports have described the effect of perioperative duloxetine administration on the postoperative pain management following knee surgery. This study aimed to determine whether perioperative duloxetine administration reduces pain following high tibial osteotomy.MethodsIn this prospective clinical trial, 35 and 33 patients receiving (40 mg/day) and not receiving duloxetine (control), respectively were enrolled. The knee pain and quality of recovery were evaluated using the numeric rating scale (NRS) scores, the frequency of analgesic drugs used, and patient-reported outcome measures, including the NRS score at rest and the Knee Injury and Osteoarthritis Outcome Score (KOOS), were compared between the groups.ResultsThe NRS scores of the duloxetine group (D) were significantly reduced compared with those of the control group (C) on postoperative day 1 (D:3.8 vs C:5.1, p = 0.022), day 7 (D:2.1 vs C:2.9, p = 0.021), and day 14 (D:1.6 vs C:2.9, p = 0.001). Non-steroidal anti-inflammatory drug administration was significantly lower in the duloxetine group than in the control group (p < 0.001). Although the KOOS score was not significantly different in several subcategories at the pre- and postoperative time-points, the Function in Sport subcategory of the KOOS was significantly improved in the duloxetine group compared with that in the control group at 3 months postoperatively (p < 0.05).ConclusionPerioperative use of duloxetine from 2 weeks before surgery to 2 weeks after surgery is advantageous in perioperative pain management and KOOS improvement following high tibial osteotomy.     

Factors affecting stability after medial opening wedge high tibial osteotomy using locking plate: A cadaveric study

ObjectivesTo investigate the effect of screw length, lateral hinge fracture, and gap filling on stability after medial opening wedge high tibial osteotomy (MOW HTO) using a locking plate.MethodsForty tibiae from fresh-frozen cadavers were randomly allocated into five groups. Group A was bicortically fixated, while Group B and Group C were unicortically fixated: 90% and 55% of drilled tunnel length, respectively. Group D was fixated using 90% length screws with a fractured lateral hinge. Group E was fixated using 90% length screws with gap filling using a bone substitute. Operated tibiae were tested under axial compressive load using a material testing machine. The medial gap changes under the serial axial load of 100–600 N and ultimate failure load were measured.ResultsGroup D showed the biggest medial gap change and lowest failure load, while Group E presented the smallest gap change and highest failure load. The medial gap changes tended to increase with shorter screw length, but the difference was not significant between Groups A, B, and C. Group C and Group D showed greater medial gap change and lower failure load compared with Group E, while not differing from Group A and Group B.ConclusionsUnicortical fixation in proximal screw holes of a locking plate was not inferior to bicortical fixation regarding axial stability in MOW HTO, although proximal screws that are too short should be avoided. Lateral hinge fracture decreased, while gap filling with bone substitute increased axial stability.     

Double-level osteotomy for severe varus osteoarthritic knees can prevent change in leg length and restore physiological joint geometry

BackgroundIt is unclear whether double-level osteotomy (DLO) combining closed-wedge osteotomy in the distal femur and open-wedge osteotomy in the proximal tibia deformity can prevent change in leg length and excessive coronal inclination of the tibial articular surface in surgical correction of the severe varus knee. The purpose of this study was to examine the postoperative change in leg length as well as radiological and clinical outcomes following DLO compared with the results obtained from knees undergoing isolated open-wedge high tibial osteotomy (OW-HTO).MethodsIn cases of severe varus knee deformity (hip–knee–ankle angle (HKA) > 10°) 29 patients undergoing DLO and 35 patients undergoing OW-HTO were included. If the predicted mechanical medial proximal tibial angle (mMPTA) was 95° or greater or the wedge size was 15 mm or greater in the surgical simulation, then DLO was considered as the surgical of option. In cases where these criteria were not met, OW-HTO was selected. All patients were followed up for a minimum of 2 years.ResultsThe changes in the length of the whole leg in the DLO and OW-HTO groups averaged 2.3 ± 4.8 mm and 9.3 ± 7.2 mm, respectively (P < 0.001). mMPTA of more than 95° was found in no knee in the DLO group.ConclusionsThis study showed that DLO could avoid leg length change and non-physiologic joint lines when performed in patients with varus HKA > 10°, and the predicted mMPTA was 95° or greater or the wedge size was 15 mm or greater in the surgical simulation.     

Cement debonding behaviors of the various tibial components of the ATTUNE knee system and its predecessors: Is a cement-in-cement revision an alternative?

BackgroundAseptic loosening remains one of the most common causes of revision of the tibial component for total knee arthroplasty. A stable bond between implant and cement is essential for appropriate long-term results. The aim of our in vitro study was to investigate the maximum failure load of tibial ATTUNE prosthesis design alternatives compared with a previous design. In addition, cement-in-cement revision was considered as a potential strategy after tibial component debonding.MethodsThe experimental investigations of the maximum failure load of the implant–cement interface were performed under optimal conditions, without potential contamination. We compared the designs of the tibial components of the ATTUNE, ATTUNE S+ and P.F.C. Sigma. In addition, we investigated the cement-in-cement revision for the ATTUNE knee system replacing it with an ATTUNE S+.ResultsThe maximum failure load showed no significant difference between P.F.C. Sigma and ATTUNE groups (P = 0.087), but there was a significant difference between the P.F.C. Sigma and the ATTUNE S+ groups (P < 0.001). The analysis also showed a significant difference (P < 0.001) between the ATTUNE and the ATTUNE S+ groups for the maximum failure load. The ATTUNE S+ cement-in-cement revision group showed a significant higher failure load (P < 0.001) compared with the P.F.C. Sigma and ATTUNE groups. No significant differences (P = 1.000) were found between the ATTUNE S+ cement-in-cement and ATTUNE S+ group.ConclusionBased on these results, we found no design-specific evidence of increased debonding risk with the ATTUNE and ATTUNE S+ components compared with the P.F.C Sigma. Furthermore, the cement-in-cement revision seems to be an alternative for the revision surgery.     

Annual trends in knee arthroplasty and tibial osteotomy: Analysis of a national database in Japan

Background

Various nationwide studies have reported differing annual trends in utilization of knee arthroplasty and tibial osteotomy. Using the Diagnosis Procedure Combination database in Japan, the present series examined annual trends and demographics in total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA) and tibial osteotomy.

Differences in impact on adjacent compartments in medial unicompartmental knee arthroplasty versus high tibial osteotomy with identical valgus alignment

BackgroundIt is unclear why medial unicompartmental knee arthroplasty (UKA) with postoperative valgus alignment causes adjacent compartment osteoarthritis more often than high tibial osteotomy (HTO) for moderate medial osteoarthritis of the knee with varus deformity. This study used a computer simulation to evaluate differences in knee conditions between UKA and HTO with identical valgus alignment.MethodsDynamic musculoskeletal computer analyses of gait were performed. The hip–knee–ankle angle in fixed-bearing UKA was changed from neutral to 7° valgus by changing the tibial insert thickness. The hip–knee–ankle angle in open-wedge HTO was also changed from neutral to 7° valgus by opening the osteotomy gap.ResultsThe lateral tibiofemoral contact forces in HTO were larger than those in UKA until moderate valgus alignments. However, the impact of valgus alignment on increasing lateral forces was more pronounced in UKA, which ultimately demonstrated a larger lateral force than HTO. Valgus alignment in UKA caused progressive ligamentous tightness, including that of the anterior cruciate ligament, resulting in compression of the lateral tibiofemoral compartment. Simultaneously, patellofemoral shear forces were slightly increased and excessive external femoral rotation against the tibia occurred due to the flat medial tibial insert surface and decreased lateral compartment congruency. By contrast, only lateral femoral slide against the tibia occurred in excessively valgus-aligned HTO.ConclusionsIn contrast to extra-articular correction in HTO, which results from opening the osteotomy gap, intra-articular valgus correction in UKA with thicker tibial inserts caused progressive ligamentous tightness and kinematic abnormalities, resulting in early osteoarthritis progression into adjacent compartments.     

Comparative outcomes of patient-specific instrumentation,the conventional method and navigation assistance in open-wedge high tibial osteotomy: A prospective comparative study with a two-year follow up

BackgroundTo compare and analyze the correction precision, clinical outcomes and complications among the three methods of performing open-wedge high tibial osteotomy (HTO), including patient-specific instrumentation (PSI), conventional method and navigation assistance.MethodsIn this prospective, single-center study, we randomly assigned patients with knee osteoarthritis in a 1:1:1 ratio to undergo Open-wedge high tibial osteotomy (OWHTO) with conventional method, navigation assistance or PSI. The primary outcome was the target/observed hip–knee–ankle (HKA) angle difference at 1 month postoperatively. Secondary outcomes were changes in the postoperative posterior tibial slope (PTS) at 1 month and clinical outcomes including knee pain on a visual analogue scale (ranging from 0 to 100, with higher scores indicating more severe pain), Lysholm and Western Ontario and McMaster Universities Osteoarthritis Index (ranging from 0 to 240) scores at 1 month, 6 months, 12 months, and 24 months.ResultsFrom 2017 through 2019, a total of 608 patients were screened; of those patients, 144 were enrolled, with 48 in each group. The primary outcome of the HKA difference was 2.6 ± 2.0° in the conventional group, 2.3 ± 1.5° in the navigation group and 0.6 ± 1.0° in the PSI group (P < 0.001). Secondary outcomes including changes in the postoperative PTS and clinical outcomes at 1 month, 6 months, and 12 months were in the same direction as the primary outcome. There were no significant differences in the complications among the three groups.ConclusionsIn the present study, none of the three methods showed superiority in objective correction precision and clinical outcomes at 2 years.     

Focal proximal fibular angle: A potential indicator of the tibial mechanical axis in opening-wedge high tibial osteotomy

BackgroundFor opening-wedge high tibial osteotomy, correct alignment is essential for a better prognosis. It is difficult to evaluate the mechanical axis of the lower extremity or tibia using a single fluoroscopic image. This study aimed to discuss the use of focal proximal fibular angle (FPFA), which can be assessed by a single fluoroscopic image, as an intraoperative indicator.MethodsEligible for analyses were 111 consecutively treated patients; for the final analyses 96 patients were included. The preoperative and postoperative medial proximal tibial angle (MPTA) and FPFA were measured. The relationship between these two angles, correction amount, weight-bearing line ratio and patient characteristics were analyzed.ResultsThe preoperative FPFA and MPTA were 96.5 ± 3.8° (mean ± standard deviation, SD) and 84.8 ± 3.0°, while the postoperative FPFA and MPTA were 87.6 ± 4.1° and 94.0 ± 3.5°, respectively. The preoperative and postoperative sums of the MPTA and FPFA were constant. The discrepancy was less than 3° in all knees, less than 2° in 92.7% knees and less than 1° in 68.8% knees. It was not correlated with age, sex, weight-bearing line ratio, or correction amount.ConclusionThe study findings confirmed the constancy of the sum of the MPTA and FPFA. The FPFA can be easily evaluated on a single fluoroscopic image of the knee. Use of the FPFA as guidance may simplify the procedure of opening-wedge high tibial osteotomy and approximately predict the tibial mechanical axis.     

Tibial tubercle osteotomy: A biomechanical comparison of two techniques

Purpose

The purpose of this study was to determine whether a modified step-cut tibial tubercle osteotomy (Maquet–Fulkerson hybrid) might produce comparable or better results than a standard oblique anteromedialization tibial tubercle osteotomy (Fulkerson type) and thus warrant the surgical need for additional cuts.