A cadaveric investigation into the demographic and bony alignment properties associated with osteoarthritis of the patellofemoral joint

An International Consensus on Evaluation and Management of Idiopathic Genu Valgum: A Modified Delphi Survey

BACKGROUND

Idiopathic genu valgum beyond physiological limits may require treatment, which is based on age, growth remaining, and the magnitude of the deformity. There is no consensus on clinical, or radiologic evaluation, indications, and management of idiopathic genu valgum, which can range from observation to surgical treatment using various modalities. If available, such guidelines will help surgeons offer optimal treatment to their patients. The aim of our study was to establish an expert consensus on the evaluation and treatment of idiopathic genu valgum.

METHODS

An international panel of 29 pediatric orthopaedic surgeons from 17 countries with clinical and research experience in the management of limb deformity participated in a modified Delphi survey. Surgeons were provided with patient and deformity characteristics and voted on 46 statements on history, clinical examination, radiographic evaluation, and treatment options for idiopathic genu valgum in round 1. Consensus was defined as when statements received ≥70% votes. Statements that were important but received <70% votes were reworded for clarity in round 2 (n=13).

RESULTS

Consensus was achieved for 28/46 statements and included obtaining a full-length standing radiograph of the lower extremities and measuring joint orientation angles. Participants did not agree to offer surgical treatment based only on the intermalleolar distance. They recommended surgical treatment if the mechanical axis falls in zone 2 or beyond on the lateral side and using guided growth by tension-band plating when the growth remaining is at least 2 years. The panel agreed on performing common peroneal nerve decompression for specific indications such as acute, opening wedge osteotomy of >20 degrees, but not for gradual correction. Consensus was not reached for indications and methods of bone age assessment, treatment when growth remaining is <1 year, indications for implant removal after guided growth in younger children, and the type of osteotomy for acute deformity correction.

CONCLUSIONS

We have generated consensus statements to guide the management of idiopathic genu valgum. Statements that lack consensus are areas for future multicenter research.

LEVEL OF EVIDENCE

Level V.

Influence of Axial Rotation Between the Femoral Neck and Ankle Joint on Kinematics in Normal Knees: A Cross-Sectional Study

BACKGROUND

The effect of axial rotation between the femoral neck and ankle joint (total rotation [TR]) on normal knees is unknown. Therefore, this study aimed to investigate the TR effect on normal knee kinematics.

METHODS

Volunteers were divided into groups large (L), intermediate (I), and small (S), using hierarchical cluster analysis based on TR in the standing position. TR was measured using three-dimensional (3D) bone models generated from CT. A two-dimensional to 3-dimensional registration technique was used to assess the spatial position and femur and tibia orientation during squat. The axial rotation, varus-valgus alignment, and anterior-posterior translation of the femur relative to the tibia were evaluated.

RESULTS

Group L had the highest TR, whereas group S had the lowest TR (L: 36.6° ± 6.0°, I: 23.2° ± 3.0°, and S: 13.8° ± 5.1°). Above 50° of flexion, femoral external rotation was greater in group S than in groups L and I. From 40° to 110°, the medial side was more anterior in group L than in groups I and S, whereas the lateral side was more posterior in group S than in groups L and I.

CONCLUSIONS

Individuals with larger TR had more femur anterior-medial translation relative to the tibia.

Bone loss on the femoral side in knees with medial osteoarthritis: Implications for kinematically-aligned total knee arthroplasty - A comparative study of lateral distal femoral angle in knees with and without osteoarthritis in the same patients

BACKGROUND

This study aimed to investigate the difference in lateral distal femoral angle (LDFA) between knees with medial osteoarthritis (mOA) and knees without osteoarthritis, and to explore the validity of the assumption that there is no bone wear on the femoral articular surface in kinematic alignment total knee arthroplasty (KA-TKA).

METHODS

The study included 69 patients with mOA on one side of the knee and but no OA on the other side. LDFA, medial proximal tibial angle (MPTA), mechanical hip-knee-ankle angle (mHKA), and arithmetic hip-knee-ankle angle (aHKA) were measured and compared between the knees. Pearson's correlation coefficient and paired t-tests were used for statistical analysis.

RESULTS

The LDFA and MPTA were significantly more varus in mOA knees than in knees non-OA knees, with differences of 1.0° ± 2.3° and 0.9° ± 2.0°, respectively. The difference between mHKA of the non-OA side and aHKA of the mOA side was not significant, indicating that it is appropriate to use aHKA as an estimation of postoperative alignment after kinematically-aligned total knee arthroplasty without anatomical correction. However, there was a significant difference in MPTA and aHKA between male and female patients in both mOA and non-OA knees.

CONCLUSIONS

The assumption that there is no bone wear on the femoral articular surface is rejectable, and the constant compensation thickness of 2 mm for cartilage wear may not be sufficient. Further research is needed to estimate the amount of bone wear in both femur and tibia side to develop more individualized surgical planning strategies in KA-TKA.

Varus osteotomy as a salvage procedure for young patients with symptomatic patellofemoral arthritis and valgus malalignment at short- to mid-term follow-up: a case series

PURPOSE

The purpose of the study was to report the clinical, functional and radiological outcome following varus osteotomy as a salvage procedure in young to middle-aged patients with patellofemoral arthritis (PFA) and associated valgus malalignment. It was hypothesized that a significant improvement in knee function and reduction in pain would be achieved. Moreover, no conversion to patellofemoral joint arthroplasty could be observed.

MATERIAL AND METHODS

Patients (< 50 years of age) that underwent varus osteotomy between 08/2012 and 01/2020 for the treatment of symptomatic PFA and associated valgus malalignment were consecutively included (minimum follow-up: 24 months). Patient-reported outcome measures (PROM; International Knee Documentation Committee subjective knee form [IKDC]), Visual Analog Scale [VAS] for pain, Tegner Activity Scale [TAS], and satisfaction with the postoperative results (1-10-scale, 10 = highest satisfaction) and weight-bearing whole-leg anteroposterior radiographs were conducted pre- and postoperatively. The change in PROM and femorotibial angle (FTA) were tested for statistical significance.

RESULTS

In total, 12 patients (14 knees) were included (66.7% female; mean age: 33.8 ± SD 6.6 years). In ten cases, lateral opening-wedge distal femoral osteotomies (DFO) were performed, of which three cases included a concomitant femoral derotation. Three medial closing-wedge DFO and one medial closing-wedge high tibial osteotomy were performed. At follow-up (55.3 ± 29.3 months), a significant improvement in knee function (IKDC: 56.4 ± 14.4 to 69.1 ± 11.2, p = 0.015) and reduction in pain (VAS for pain: 3.5 [interquartile range 2.3-5.8] to 0.5 [0-2.0], p = 0.018) were observed. Patients were able to reach their preoperative sporting activity level (TAS: 3.0 [3.0-4.0] to 3.5 [3.0-4.0], p = 0.854) and were highly satisfied with the postoperative result (9.0 [6.5-10]). Additionally, a significant correction of valgus malalignment was observed (5.0° ± 2.9° valgus to 0.7° ± 3.2° varus, p < 0.001). Regarding complications, two re-osteosyntheses were performed due to loss of correction and delayed union. No conversion to patellofemoral arthroplasty occurred.

CONCLUSION

In patients with symptomatic PFA and associated valgus malalignment, varus osteotomy as a salvage procedure achieved a significant improvement in knee function and reduction in pain. No conversion to patellofemoral joint arthroplasty occurred at short- to mid-term follow-up.

LEVEL OF EVIDENCE

Retrospective case series, Level IV.

Torsional Deformity Significantly Impacts Lateral Ankle Radiographic Imaging Parameters

Background Optimal lateral ankle imaging is important for the diagnosis and treatment of multiple ankle conditions. The effects of limb deformity on lateral ankle imaging are not well described and are clarified in this osteological study. Materials and methods We utilized an osteological collection and imaged all specimens after the first positioning of the talus in the lateral position and positioning the tibia and fibula to match. We then measured the relative positions of the tibia and fibula and their widths to calculate standard ratios. All measurements were evaluated for reliability using intra-class correlation coefficients. Multiple regression analysis determined how patient characteristics, tibial torsion, and medial proximal tibial angle affected various lateral ankle imaging ratios. Results The intra-class correlation coefficient was excellent for all measurements. In the multiple regression analysis, all five imaging ratios had at least one statistically significant outcome. The anterior tibiofibular interval (ATFI)-tibial width (TW) ratio (ATFI:TW) had only one association with sex and had the lowest standard deviation. All other parameters had variation with tibial torsion and/or medial proximal tibia angle (MPTA). The mean ATFI was 1.06 ± 0.21 cm and 1.19 ± 0.23 cm for females and males, respectively. Conclusions Patient sex and tibial torsion impacted the fidelity of lateral imaging parameters. ATFI:TW may pose the greatest utility given its minimal association with deformity parameters and low standard deviation.

Tibial morphology of symptomatic osteoarthritic knees varies according to location: a retrospective observational study in Japanese patients

This study analyzed 31 patients with symptomatic osteoarthritic knees scheduled to undergo knee arthroplasty or high tibial osteotomy and demonstrated shape variations in their proximal tibia using an average three-dimensional (3D) bone model. Preoperative computed tomography of the affected knees was reconstructed as 3D bone models using a triangle mesh of surface layers. The initial case was defined as the template, and the other models were reconstructed into homologous models with the same number of mesh vertices as that in the template. The corresponding mesh vertices of the other models were averaged to evaluate the spatial position on the particular mesh vertex of the template. This was applied to all the mesh vertices of the template to generate the average 3D model. To quantify the variation in surface geometry, average minimum distance from the average bone model to 31 models was recorded. The medial proximal tibial cortex (1.63 mm) revealed lesser variation compared to the tibial tuberosity (2.50 mm) and lateral cortex (2.38 mm), (p = 0.004 and p = 0.020, respectively). The medial tibial plateau (1.46 mm) revealed larger variation compared to the lateral tibial plateau (1.16 mm) (p = 0.044). Understanding 3D geometry could help in development of implants for arthroplasty and knee osteotomy.

A Cadaveric Anatomical Study of the Relationship between Proximal Tibial Slope and Coronal Plane Deformity

Medial proximal tibial angle (MPTA) and posterior proximal tibial angle (PPTA) are commonly used to characterize the geometry of proximal tibia and are important considerations in lower extremity realignment procedures and total knee arthroplasty. This study utilized a large cadaveric collection to explore relationships between tibial slope and coronal plane deformity of the tibia. We utilized 462 well-preserved skeletons (924 tibiae), excluding any with fracture or obvious rheumatologic or infectious findings. Custom cards were made with different sized arcs on the bottom surface, so that they could rest on the anterior and posterior aspects of the medial and lateral tibial plateaus of each bone to measure PPTA. Previously measured MPTA values for the same bones were also utilized. Multiple regression analysis was used to determine relationship between MPTA and medial and lateral PPTAs. The mean age was 56 ± 10 years, with 13% female and 31% African American (remainder Caucasian). The mean MPTA was 87.2 ± 2.4 degrees. The mean medial plateau PPTA was 81.5 ± 3.8 degrees and mean lateral plateau PPTA was 81.3 ± 3.7 degrees. Regression analysis found that MPTA was significantly associated with both medial and lateral PPTAs (standardized betas 0.197 and 0.146, respectively, p < 0.0005 for both). There was a significant correlation between lateral and medial PPTAs (r = 0.435, p = 0.03). The clinical significance of these findings warrants further investigation and emphasizes the importance of carefully assessing the sagittal plane when planning reconstruction of a tibia with varus or valgus deformity, particularly high tibial osteotomies.

An Anatomical Evaluation of the Trapezium and Its Relationship to Basilar Joint Osteophytic Change

BACKGROUND

To perform a comprehensive osteologic investigation into trapezium anatomy and investigate the relationship between anatomical factors and osteophyte formation, focusing on sex-specific differences.

METHODS

This was a cadaveric study involving 1233 trapezia and first metacarpals. Two subgroups ("Control" and "Main Study") were established. The "Control" cohort was used to identify features of the trapezium in specimens devoid of osteophytic change. The prevalence and severity of osteophytic change were investigated in the "Main Study" cohort. Sex differences were specifically assessed. Regression analyses were used to identify factors associated with osteophyte formation.

RESULTS

Three discrete surface morphologies exist at the trapezium trapeziometacarpal (TM) facet: heart, quadrilateral, and bean. Controlling for height, men have a larger trapezium TM facet surface area. However, the trapezium assumes the same off-center saddle shape in both sexes. The presence of osteophytes at the basilar joint is a common finding; no differences in osteologic prevalence exist between sexes. The progression of osteophytic change complements the radiographic Eaton-Littler classification system. The trapezium TM facet increases the surface area with incremental osteophyte involvement, with the degree of surface area expansion correlated with increases in the severity of osteophytic change. Increased age, increased surface area, bean morphology, and decreased volar joint depth are associated with more severe osteophyte formation.

CONCLUSIONS

Anatomical features of the trapezium may contribute to osteophyte development. Although the prevalence of osteophytic disease appears equal between sexes, sex differences exist in some anatomical parameters. These differences may help explain the increased prevalence of symptomatic basilar joint disease in women.

The distal femur trochlear groove appears to compensate for tibial deformity but not femoral deformity in an investigation of five-hundred and seventy-nine cadaveric skeletons

BACKGROUND

The etiology of patellofemoral disorders is multifactorial. Preoperative patellofemoral anatomy evaluation is of great importance in patients undergoing surgery for patellofemoral disorders. Although anatomical risk factors of patellofemoral disorders have been thoroughly investigated in clinical and radiological studies, there are sparse data regarding the association between trochlear dysplasia with other anatomical parameters. This study sought to explore those associations using a large osteological collection.

METHODS

Five-hundred and seventy-nine cadaveric skeletons were obtained from the Hamann-Todd osteological collection. Mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), femoral version, tibial torsion, lateral position of the tibial tubercle, and femoral length were modeled as predictors of medial and lateral flange height of the distal femur trochlea at various degrees of knee flexion.

RESULTS

The average age and standard deviation for the 1158 lower extremities analyzed was 55.9 ± 10.2 years. There were 500 males (86%) and 79 females. Increasing MPTA or tibial valgus predicted increasing lateral femoral flange height at 0, 30, and 50 degrees of knee flexion [(standardized beta 0.111, p = 0.01), (standardized beta 0.129, p < 0.001), and (standardized beta 0.186, p < 0.001), respectively]. Increasing internal tibial torsion predicted increased medial flange height at 30 and 50° [(standardized beta - 0.114, p = 0.006), (standardized beta - 0.108, p = 0.006), respectively]. Increased femoral retroversion predicted increasing lateral flange height at 0 and 30 degrees [(standardized beta - 0.105, p = 0.005), (standardized beta - 0.098, p = 0.004), respectively].

CONCLUSIONS

To maintain the equilibrium necessary for effective patellar tracking, the depth of trochlear groove appears to effectively compensate for some of the anatomical parameters of the proximal tibia associated with patellofemoral disorders, and appears to be less influenced by femoral alignment. The clinical relevance of these findings warrants further investigation, and emphasizes the importance of carefully assessing the lower limb alignment in the management of patellofemoral disorders.

Patellar Morphology and Osteoarthritis: A Cadaveric Analysis

Previous studies have attempted to characterize patellar morphology and its relation to patellofemoral osteoarthritis but have utilized relatively small samples. We designed a large-scale cadaveric analysis to elucidate any potential relationship. Patellar morphology in 1,032 patellae was characterized using patellar facet concavity patterns initially developed by Wiberg and using the ratio of the lateral and medial facet lengths. Patellofemoral arthritis grading for specimens was previously completed based primarily on osteophytic burden. The average age at time of death was 56 ± 10 years. Wiberg's grading returned kappa values of 0.43 for intrarelator reliability and 0.27 for interrelator reliability. Using multiple regression analysis, Wiberg's type II was found to be correlated with patellofemoral arthritis (p = 0.003). Lateral to medial facet ratio measurements returned intraclass coefficients of 0.91 for intrarelator reliability and 0.85 for interrelator reliability. There was no association between lateral to medial facet ratio and osteoarthritis. Regression analysis between Wiberg's typing and lateral-to-medial ratio (L:M) resulted in a coefficient of determination of 0.14. To our knowledge, this is the largest study evaluating the relationship between patellar morphology and arthritis. Although there was a relationship between Wiberg's type II and patellofemoral arthritis, the Wiberg systems was not easily reproducible in our study and returned a correlation with arthritis different then anatomically expected. A more reproducible system of lateral to medial facet ratio was investigated but did not find an association with arthritic changes. Given these findings, we did not find a patella morphology grading system which is both reliable and valid in regard to association with patellofemoral arthritis.

High prevalence of patellofemoral osteoarthritis in China: a multi-center population-based osteoarthritis study

BACKGROUND

To describe the prevalence and risk factors of patellofemoral osteoarthritis (PFOA) among Chinese residents.

METHODS

A multi-center population-based osteoarthritis study was conducted in 2014. Residents aged ≥ 50 years old were recruited using a cluster sampling method. Subjects completed a home interview and physical examination and had skyline view of radiographs at patellofemoral (PF) joints. Radiographs were read by two trained musculoskeletal researchers, and discordance of a subject's PFOA status between two readers was adjudicated with a third musculoskeletal researcher present. Radiographic OA at PF joint was defined if osteophytes (OST) score was ≥ 2 or if joint space narrowing (JSN) score was ≥ 2 with concurrent grade 1 OST in the PF joint.

RESULTS

Of 3446 subjects (63.0% women) included in this analysis, the prevalence of radiographic PFOA was 23.9% (20.5% men vs. 25.8% women). Prevalence of lateral radiographic OA was higher than medial radiographic OA at PF joint. Grades of both osteophytes and joint space narrowing in the lateral patellofemoral compartment were higher than those in the medial patellofemoral compartment (all P values < 0.001). Women, older age, higher BMI, and fewer years of education were significantly associated with higher prevalence of radiographic PFOA, osteophytes, and joint space narrowing.

CONCLUSION

Prevalence of radiographic PFOA was high among Chinese population. Key Points • The multi-center population-based osteoarthritis study shows the prevalence of radiographic PFOA was high among Chinese population. • Older age, female gender, obesity, and few years of education were associated with a high risk of PFOA. • Prevalence of lateral radiographic OA was higher than medial radiographic OA at PF joint.

Significant proportion of severe lateral osteoarthritis in korean patients have non-valgus knee alignment with milder clinical manifestation

BACKGROUND

Knee malalignment is strongly associated with risk of knee osteoarthritis (OA). Although several studies have described the relationship between valgus knee alignment and incidence of severe lateral OA, little research is available on the association with non-valgus (neutral or varus) knee alignment. Therefore, we performed a retrospective study to determine: 1) whether a substantial proportion of severe lateral OA patients have non-valgus knee alignment and 2) whether there are any difference in clinical manifestations between patients with valgus and non-valgus alignment.

HYPOTHESIS

A large proportion of severe lateral OA patients in Korea have non-valgus knee alignment.

PATIENTS AND METHODS

The medical records of 647 patients (825 knees) who visited our outpatient clinic from 2008 to 2018 and were diagnosed with lateral OA were retrospectively reviewed. Knee OA severity was evaluated according to the Kellgren-Lawrence (K-L) grading system and those with K-L grade 3 or 4 were enrolled in this study. Alignment was measured by the hip-knee-ankle angle on full-limb radiographs and classified as varus (<180°), neutral (180°), or valgus (>180°). Patients with K-L grade 4 lateral OA (bone-on-bone arthritis) were divided into two groups according to knee alignment (non-valgus or valgus) and compared for recommended treatment (surgery or conservative treatment) as an indicator of clinical manifestations.

RESULTS

Of the 825 knees, 67.1% (553/825) were K-L grade 3 or 4. Of these 553 K-L grade 3/4 knees, 20.4% (113/553) had neutral, 23.3% (129/553) varus, and 56.2% (331/553) valgus knee alignment. Notably, 43.8% (242/553) of the K-L grade 3 or 4 knees had non-valgus alignment (95% CI: 40%-48%, exact binomial test). Of the K-L grade 4 patients (263 knees), the proportion recommended conservative treatment was significantly higher in the non-valgus group (80.2% (69/86)) than the valgus group (62.1% (110/177)) (χ² test, p=0.003)).

CONCLUSION

In contrast to the widespread belief that most lateral OA patients have valgus knee alignment, a substantial proportion of Korean patients with severe lateral OA in this study had non-valgus alignment. In addition, these non-valgus alignment patients presented with significantly milder clinical manifestations in bone-on-bone lateral OA than valgus patients. While orthopaedic surgeons tend to initially consider surgery for bone-on-bone lateral OA, full-limb radiographs should be acquired to assess knee alignment, because patients with non-valgus alignment may be treated conservatively.

LEVEL OF EVIDENCE

III, Case control study.

Hemiepiphysiodesis for Idiopathic Genu Valgum Using Physeal Staples Versus Tension-Band Plating: A Systematic Review

This review assesses the outcomes of hemiepiphysiodesis in patients with idiopathic genu valgum (IGV) treated with physeal staples vs tension-band plating (TBP). A systematic review of the literature was conducted to identify articles examining the use of physeal staples vs TBP for the treatment of IGV in skeletally immature patients. No significant difference in overall mean deformity correction (P=.92) or correction per month (P=.61) was observed between groups. Repeat hemiepiphysiodesis was more common in patients who underwent TBP vs physeal staples (P=.05). Tension-band plating did not yield significantly improved results compared with physeal staples in skeletally immature patients with IGV. [Orthopedics. 2019; 42(6):e485-e491.].

The Natural History of Lower Extremity Malalignment

BACKGROUND

Lower extremity malalignment is a common problem presented to pediatric orthopaedists. Risk for early arthritis is often a concern among parents seeking advice and treatment. We seek to review previous research with regard to the natural history of malalignment.

METHODS

A search of available literature on PubMed was constructed to capture articles covering the natural history of malalignment, secondary to childhood fracture as well as congenital and acquired pediatric deformity. In order to remain strictly relevant to pediatrics, articles reviewing deformities acquired in adulthood were not referenced. Biomechanical data and animal studies were included when deemed appropriate.

RESULTS

High-quality data with regard to long-term risk of arthritis due to malalignment is lacking. Through a combination of biomechanical data, animal models, and a small body of longitudinal clinical data, it is clear that some patients with malalignment progress to early arthritic change. Unfortunately, detailed risk factors of who is at high risk versus low risk remains difficult to determine.

CONCLUSIONS

Treatment of minor lower extremity malalignment is not supported by the current orthopaedic literature. Treatment plans should focus on the presence of symptoms, and in asymptomatic but severe cases. Even in more severe cases, strong evidence to support prophylactic realignment is not available. Evidence to suggest that preventative realignment is superior to intervention at the time of symptom onset does not exist.

Highly variable coronal tibial and femoral alignment in osteoarthritic knees: a systematic review

PURPOSE

There is a lack of knowledge about coronal alignment variability in osteoarthritic knees. Therefore, the purpose of this article was to systematically review the literature and collect data about the lower limb alignment including hip-knee-ankle angle (HKA), femoral mechanical angle (FMA), tibial mechanical angle (TMA) and the joint line convergence angle (JLCA) in osteoarthritic knees.

METHODS

A systematic review was performed using the electronic databases MEDLINE (PubMed), EMBASE and Google Scholar. The following keywords were used: (morphology OR geometr* OR anatomy OR alignment OR phenotypes), (coronal OR neutral OR varus OR valgus), (knee OR lower limb OR femur OR tibia) and (osteoarthritis OR arthritis). Out of 110 full-text articles retrieved, 15 studies were included. Demographic information included author's names, year of publication, imaging modality, sample size and patient demographics (i.e. sex, age, etc.). Descriptive statistics, such as means, ranges, and measures of variance [e.g. standard deviations, 95% confidence intervals (CI)] for all angles (HKA, FMA, TMA, JLCA) are presented.

RESULTS

Thirteen studies reported mean overall HKA angles ranging from 163.5° ± 2.3° to 179.9° ± 4.8°. The mean HKA angles in females were between 164.1° ± 7.2° and 178.8° ± 4.8°, and in males between 163.4° ± 5.5° and 177.4° ± 3.9°. The lowest and highest reported HKA angles were - 27.7° and + 22.0°, respectively. Seven studies reported mean FMA angles. Mean values ranged from 92.7° ± 2.7° valgus to 88.6° ± 2° varus. The reported mean FMAs for male were 87.9° ± 0.5° to 90.7° ± 3° and for female 89.91° ± 2.8° to 92.9° ± 3.1°. Six studies reported mean TMA values. TMA ranged from 81.7° ± 3.9° varus to 87.7° ± 4.1° varus. Only three studies reported mean JLCA angles, which ranged from - 4.3° to - 6.4° ± 3.8°.

CONCLUSION

Osteoarthritic knees showed a huge variation in overall coronal limb alignment as well as in femoral and tibial coronal alignment. Current total knee arthroplasty (TKA) alignment philosophies and preoperative planning do not sufficiently consider these variation, which might be one reason for unhappy knees after TKA.

LEVEL OF EVIDENCE

IV, systematic review.

Patellofemoral dysbalance and genua valga: outcome after femoral varisation osteotomies

INTRODUCTION

Patellofemoral dysbalance may be caused by trochlear dysplasia, an elevated TTTG distance, femoral or tibial torsional deformities, patella alta, or a genu valgum. The surgical procedure for the treatment of a genu valgum is varisation osteotomy, usually in the femoral aspect. Several authors believe that a genu valgum is one cause of patellofemoral dysbalance, but studies about the outcome of the treatment with a varisation osteotomy are rare.

MATERIALS AND METHODS

Nineteen knees in 18 patients, aged on average 28 (16-52) years were investigated in a retrospective study. The patients had symptoms of patellofemoral instability or anterior knee pain due to a genu valgum, without symptoms of a lateral femorotibial compartment. All patients underwent a femoral varisation osteotomy. The diagnostic investigation prior to surgery included full-leg radiographs and torsional angle CT scans. The pre-surgery and follow-up investigation included the visual analog scale (VAS), the Kujala score, the Japanese Knee Society score, the Lysholm score.

RESULTS

The mean duration of follow-up was 44(10-132) months. The mean preoperative mechanical valgus was 5.6° (range 4-10°). Twelve patients mentioned patellar instability as the main symptom while 14 mentioned anterior knee pain. No redislocation occurred in the follow-up period. Anterior knee pain on the VAS (p value < 0.001) was significantly reduced (5.6-2.1). The Japanese Knee Society score improved from 87 to 93 (p value 0.013) points, the Kujala score improved significantly from 72 to 87 (p value 0.009), and the Lysholm score significantly from 76 to 92 (p value < 0.001).

CONCLUSION

Genua valga can lead to patellofemoral dysbalance, treatment of this condition is femoral varisation osteotomy. In this study, patellofemoral stability was achieved and anterior knee pain was significantly reduced. Significant improvements in clinical scores proved the success of the treatment.

LEVEL OF EVIDENCE

IV, case series.

An Anatomic Investigation Into the Relationship Between Posterior Condylar Offset and Posterior Tibial Slope of One Thousand One Hundred Thirty-Eight Cadaveric Knees

BACKGROUND

Posterior condylar offset (PCO) and posterior tibial slope (PTS) have critical consequences in total knee arthroplasty, especially with regards to sagittal plane balancing. However, there has only been limited investigation into the functional consequences of each, and there have only been anecdotal observations regarding any associations between PCO and PTS.

METHODS

In a large osteological study of 1138 knees, standardized measurements of PCO and PTS were taken using previously described techniques on specimens of different age, race, and gender. Multiple linear regression was performed to determine the independent predictors of medial and lateral PTS.

RESULTS

Mean standardized medial PCO was greater than lateral PCO (1.22 ± 0.16 vs 1.15 ± 0.19 mm, P < .001) and medial PTS was greater than lateral PTS (7.3 ± 3.8° vs 5.7 ± 3.7°, P < .001). Decreasing PCO, female gender, and African-American race were associated with both increased medial and lateral PTS. Neither age nor femoral length correlated with medial or lateral PTS.

CONCLUSION

These data are the first to quantify that an inverse correlation between PCO and PTS exists. This relationship represents an important area for future biomechanical and clinical studies.

Differences in Medial and Lateral Posterior Tibial Slope: An Osteological Review of 1090 Tibiae Comparing Age, Sex, and Race

BACKGROUND

Injuries to the anterior cruciate ligament (ACL) are common, and a number of knee morphological variables have been identified as risk factors for an ACL injury, including the posterior tibial slope (TS). However, limited data exist regarding innate population differences in the TS.

PURPOSE

To (1) establish normative values for the medial and lateral posterior TS; (2) determine what differences exist between ages, sexes, and races; and (3) determine how internal or external tibial rotation (as occurs during sagittal knee motion) influences the stereotactic perception of the TS.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 545 cadaveric specimens (1090 tibiae) were obtained from the Hamann-Todd osteological collection. Specimens were leveled in the coronal, sagittal, and axial planes using a digital laser. Virtual representations of each bone were created with a 3-dimensional digitizer apparatus. The TS of the medial and lateral tibial plateaus were measured using techniques adapted from previous radiographic protocols. Medial and lateral TS were then again measured on 200 tibiae that were internally and externally rotated by 10° (axially).

RESULTS

The mean (±SD) medial TS was 6.9° ± 3.7° posterior, which was greater than the mean lateral TS of 4.7° ± 3.6° posterior ( P < .001). Neither the medial nor lateral TS changed with age. Women had a greater mean TS compared with men on both the medial (7.5° ± 3.8° vs 6.8° ± 3.7°, respectively; P = .03) and lateral (5.2° ± 3.5° vs 4.6° ± 3.5°, respectively; P = .04) sides. Black specimens had a greater mean medial TS (8.7° ± 3.6° vs 5.8° ± 3.3°, respectively; P < .001) and lateral TS (5.9° ± 3.3° vs 3.8° ± 3.5°, respectively; P < .001) compared with white specimens. Axial rotation was shown to increase the perception of the medial and lateral TS ( P < .001).

CONCLUSION

The medial TS was shown to be greater than the lateral TS. Important sex- and race-based differences exist in the TS. This study also highlights the role of axial rotation in measuring the TS.