The Tibial Tubercle-Trochlear Groove Distance Is Greater in Patients With Patellofemoral Pain: Implications for the Origin of Pain and Clinical Interventions

Tibial Tubercle Osteotomy: Indications, Outcomes, and Complications

PURPOSE OF REVIEW

The tibial tubercle osteotomy (TTO) is a versatile surgical technique used to treat a range of patellofemoral disorders, including patellar instability, painful malalignment, focal chondral defects, and patellar maltracking that have failed conservative therapies. TTO is a personalized procedure that can be tailored to the pathoanatomy of the patient based on physical examination and imaging. The complication rate associated with TTO strongly depends on the indication for surgery, the severity of the patient's condition, and the surgical approach. Despite the literature on TTO, to our knowledge, no single source has addressed the indications, techniques, outcomes, and complications of this procedure. The purpose of this article is to serve as such a valuable resource.

RECENT FINDINGS

Highlights from recent studies we would like to emphasize are two-fold. First, maintaining a distal cortical hinge yields lower complication rates than osteotomies involving complete tubercle detachment with classic or standard techniques. Second, based on current evidence, TTO consistently provides symptomatic relief, and most patients can return to work or sport at their pre-operative level within 3 and 6 months, respectively. TTO is a personalizable surgical technique that may be utilized for multiple patellofemoral disorders and is associated with good outcomes.

Biomechanical and biological factors of sexual dimorphism in anterior knee pain: Current concepts

Female gender is one of the commonly mentioned risk factors for anterior knee pain (AKP), among a spectrum of other factors including anatomical, biomechanical, hormonal, behavioral and psychological elements contributing to its development. Despite the focus on individual risk factors, there's a notable gap in comprehending how gender influences and interacts with other risk factors. The objective of this review was to identify and emphasize the connections between these interactions, gender-related risk factors for AKP, and the potential mechanisms that explain their associations with other risk factors, aiming to aid in the creation of precise prevention and treatment approaches. Gender influences the majority of risk factors for AKP, including anatomical, biomechanical, hormonal, behavioral and psychological factors. Women have on average smaller patellae, higher patellofemoral cartilage stress and for AKP, disadvantageous trochlear morphology, ligament and muscle composition and unfavorable neuromuscular control pattern. In contrast, men show on average an increased ability to strengthen their hip external rotators, which are both protective against AKP. Particularly in kinetic and kinematic analysis, men have been shown to have a distinctly different risk factor profile than women. Sex hormones may also play a role in the risk of AKP, with estrogen potentially influencing ligamentous laxity, increasing midfoot loading and affecting neuromuscular control of the lower extremities and testosterone positively affecting muscle mass and strength. The higher incidence of AKP in women is likely due to a combination of slightly increased risk factors. Although all risk factors can be present in both men and women and the holistic evaluation of each individual's risk factor composition is imperative regardless of gender, knowing distinctive risk factors may help with focused evaluation, treatment and implementing preventive measures of AKP.

A decreased tibial tuberosity-trochlear groove distance is associated with lateral patellofemoral joint degeneration after implantation of medial fixed-bearing unicompartmental knee arthroplasty - a minimum five year follow-up

PURPOSE

The influence of lateral patellofemoral osteoarthritis (PFOA) in medial unicompartmental knee arthroplasty (UKA) is controversial. Our aim was to identify radiographic factors that may lead to progressive PFOA after implantation of a fixed-bearing medial UKA and their impact on patient-reported outcomes (PROMs).

METHODS

A retrospective consecutive cohort of patients undergoing medial UKA with a minimum follow-up of 60 months between September 2011 and January 2017 was identified. All UKAs had a fixed-bearing design with cemented femoral and tibial components. PROMs included documentation of the Oxford Knee Score (OKS). The following radiographic parameters were evaluated on conventional radiographs and computer tomography (CT) scans: patella tilt angle, patella congruence angle, Caton-Deschamps index, medial and lateral patellofemoral degeneration (Kellgren-Lawrence Classification (KL)), mechanical anteroposterior axis, femoral torsion, tibial tuberosity to trochlear groove distance (TTTG), anteroposterior translation of the femoral component. A hierarchical multiple regression analysis and partial Pearson correlation analysis (SPSS) were used to evaluate for predictors of progression of lateral PFOA.

RESULTS

Forty-nine knees allowed PFOA assessment and had an average follow-up of 62 months (range 60-108). Twenty-three patients did not exhibit any progression of lateral PFOA. Twenty-two progressed with 1 stage, whereas four had progressed 2 stages according to the KL classification. TTTG negatively correlated with progressive lateral PFOA (r =  - 0.436, p = 0.01). Progression of lateral PFOA did not correlate with OKS at last follow-up (p = 0.613).

CONCLUSION

A decreased TTGT correlated with radiographic progression of lateral PFOA after medial fixed-bearing cemented UKA. PFOA however did not influence PROMs at a minimum of five years postoperatively.

Should isolated superolateral Hoffa's fat pad edema identified by MRI be reported or ignored in adolescent patients?

BACKGROUND AND OBJECTIVE

The presence of superolateral Hoffa's fat pad (SHFP) edema is associated with several morphometric measurements related to patellar alignment and trochlear morphology. Our aim is to evaluate management implications in adolescent patients with isolated superolateral Hoffa's fat pad edema on MRI.

MATERIALS AND METHODS

Retrospective review of 117 adolescents with knee MRI (mean 14.8 years old) with isolated superolateral Hoffa's fat pad edema. Patients with edema were separated into two groups based on the number of MRI axial slices involved with edema: group 1 (G1) of 27 patients with 1 slice vs group 2 (G2) of 90 patients with 2 or more slices. A comparison control group was used (45 patients who had normal MRI knees). Data points included % referral for physical therapy (PT) or surgery, Hoffa's fat pad edema, tibial tubercle-trochlear groove (TT-TG) distance and lateral trochlear inclination (LTI) angle. Fisher's exact and independent t-tests, ANOVA and regression models were used for statistical analysis.

RESULTS

There is statistically significant difference between Hoffa's fat pad edema patients and control regarding PT referral with G1: 70%, G2: 76%, and control: 53% (p = 0.03). There is statistically significant difference between these groups regarding TT-TG measurements with higher values in edema groups; G1: 11.9 mm±4.1, G2 13 mm ±4.1, and control 8.7 mm±3.6, (p = 0.001). There was a statistically significant association between edema and increased TT-TG distance (p = 0.001) but not LTI angle (p = 0.2).

CONCLUSION

MRI identification of isolated superolateral Hoffa's fat pad edema is positively associated with TT-TG distance and its presence is associated with higher referral rates to physical therapy for patella maltracking.

Predisposing factors for Hoffa's fat pad syndrome: a systematic review

BACKGROUND

Hoffa's fat pad syndrome has been defined as impingement of Hoffa's fat pad, leading to oedema and fibrosis. The primary aim of this systematic review was to identify morphological differences in Hoffa's fat pad between patients with and without Hoffa's fat pad syndrome, evaluating them as risk factors predisposing to its development. The secondary aim was to summarize and evaluate current evidence pertaining to the management of Hoffa's fat pad syndrome.

MATERIALS AND METHODS

The protocol for this review was prospectively registered (PROSPERO registration: CRD42022357036). Electronic databases, currently registered studies, conference proceedings and the reference lists of included studies were searched. All studies evaluating differences in Hoffa's fat pad anatomy under imaging between patients with and without Hoffa's fat pad syndrome were included, as well as those exploring epidemiological factors predisposing to its development (ethnicity, employment status, sex, age and BMI), and studies reporting on the effect of treatment on Hoffa's fat pad morphology.

RESULTS

A total of 3871 records were screened. Twenty one articles satisfied the inclusion criteria, evaluating 3603 knees of 3518 patients. Patella alta, increased tibial tubercle-tibial groove distance, and increased trochlear angle were found to predispose the development of Hoffa's fat pad syndrome. Trochlear inclination, sulcus angle, patient age and BMI were not associated with this condition. The link between Hoffa's fat pad syndrome and ethnicity, employment, patellar alignment, Hoffa's fat pad composition, physical activity and other pathological processes cannot be established due to lack of evidence. No studies reporting on treatment for Hoffa's fat pad syndrome were identified. Though weight loss and gene therapy may provide symptomatic relief, further research is required to corroborate these claims.

CONCLUSION

Current evidence suggests that high patellar height, TT-TG distance, and trochlear angle predispose the development of Hoffa's fat pad syndrome. In addition, trochlear inclination, sulcus angle, patient age and BMI do not seem to be associated with this condition. Further research should explore the link between Hoffa's fat pad syndrome and sport as well as other conditions pertaining to the knee. In addition, further study evaluating treatment approaches for Hoffa's fat pad syndrome is required.

The effect of native knee rotation on the tibial-tubercle-trochlear-groove distance in patients with patellar instability: an analysis of MRI and CT measurements

BACKGROUND

This study aimed to quantify the effect of lower limb rotational parameters on the difference in the tibial-tubercle-trochlear-groove (TTTG) distance when assessed with magnetic resonance imaging (MRI) and computed tomography (CT) in patients with patellar instability. It was hypothesized that an increased native knee rotation angle significantly contributes to an underestimation of TTTG by MRI.

METHODS

Forty patients with patellar instability who had undergone standard radiographs, MRI and CT scans were included in this retrospective study. A musculoskeletal radiologist assessed all imaging for TTTG, femoral and tibial rotation, knee rotation and flexion angle, and trochlear dysplasia. ΔTTTG was defined as the TTTG measured on MRI subtracted from the TTTG measured on CT. Statistical analysis determined the effect of these parameters on the calculated difference between TTTG when measured on CT and MRI.

RESULTS

Equal knee flexion in MRI and CT resulted in a ΔTTTG of 0.1 ± 0.3 mm compared to 4.0 ± 3.3 mm in patients with different knee flexion angles in both imaging acquisitions (p = 0.036). The knee rotation angle measured on CT (native knee rotation angle) was negatively correlated with ΔTTTG (r = - 0.365; p = 0.002), while neither tibial nor femoral rotation showed any associations with TTTG (n.s.). Trochlear dysplasia did not show any significant correlation with ΔTTTG, regardless of classification by Dejour or Lippacher (n.s.). Both the native knee rotation angle and the MRI knee flexion angle were independent predictors of ΔTTTG, yet with an opposing effect (knee rotation: 95% Confidence Interval [CI] for β - 0.468 to - 0.154, p < 0.001; knee flexion 95% CI for β 0.292 to 0.587, p < 0.001). Patients with a native knee rotation angle > 20° showed a ΔTTTG of - 5.8 ± 4.0 mm (MRI rather overestimates TTTG) compared to 0.9 ± 4.1 mm Δ TTTG (MRI rather underestimates TTTG) in patients with < 20° native knee rotation angle.

CONCLUSION

The native knee rotation angle is an independent, inversely correlated predictor of ΔTTTG, thus opposing the effect of knee flexion during MRI acquisition. Consequently, these results suggest that not only knee flexion but also knee rotation should be appreciated when assessing TTTG during patellar instability diagnostic evaluation as it can potentially lead to a false estimation of the TTTG distance on MRI.

LEVEL OF EVIDENCE

Level III.

Changes in Anatomic Risk Factors for Patellar Instability During Skeletal Growth and Maturation

BACKGROUND

Several anatomic risk factors have been identified in the pathogenesis of patellofemoral instability. The literature is sparce regarding how these anatomic risk factors change during skeletal growth and development.

HYPOTHESIS

The anatomic risk factors associated with patellar instability change significantly during skeletal growth and maturation with different patterns in male versus female patients.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Magnetic resonance imaging data from 240 unique, asymptomatic knees (7-18 years of age; 50% female) were used to measure patellar height (Caton-Deschamps index), lateral patellar tilt angle, trochlear height, trochlear groove depth, trochlear sulcus angle, and tibial tubercle-trochlear groove (TT-TG) distance. Linear regression was used to test the associations between age and anatomic findings. Two-way analysis of variance with Holm-Šídák post hoc test was used to compare anatomic characteristics between sexes in 3 age groups: prepubertal school-aged children (7-10 years old), early adolescents (11-14 years old), and late adolescents (15-18 years old).

RESULTS

Patellar height (female sex), lateral patellar tilt angle (male sex), and trochlear sulcus angle (both sexes) decreased with age (P < .001). Trochlear height, depth, and TT-TG distance increased with age in both male and female participants (P < .02). Male participants had a larger sulcus angle (by 5.3°± 1.6° at age 11-14 years) and greater trochlear height (by >5 mm across medial, central, and lateral regions at age 15-18 years) than age-matched female participants (P < .01). We found no other sex-related differences in quantified anatomic features (P > .1).

CONCLUSION

The findings partially support our hypothesis indicating significant age-related changes in all quantified features, which were not different between male and female participants except for trochlear sulcus angle in early adolescence and trochlear height in late adolescence. In general, the majority of anatomic risk factors for patellar instability change with maturity in a direction that assists in reducing the risk of patellar instability and/or dislocation. The only outlier is the TT-TG distance, which increased by age, and in our oldest cohort of patients, the mean fell below the normal adult range. The current observations highlight the importance of age in the interpretation of risk for injury as well as the need for further studies to identify intrinsic and extrinsic factors that may result in abnormal development of these anatomic features during skeletal growth and maturation.

Tibial tubercle-Roman arch (TT-RA) distance is superior to tibial tubercle-trochlear groove (TT-TG) distance when evaluating coronal malalignment in patients with knee osteoarthritis

OBJECTIVES

To verify tibial tubercle-Roman arch (TT-RA) distance is superior to tibial tubercle-trochlear groove (TT-TG) distance in preoperative assessment of patellofemoral joints in patients with knee osteoarthritis.

METHODS

Patients with knee osteoarthritis from 2016 to 2020 were considered eligible for inclusion in this study. We divided the patients into valgus group and varus group and did 1:1 matching for the two groups. We measured the TT-TG distance, TT-RA distance, patellar height, patella tilt, hip-knee-ankle (HKA) angle, and Iwano's classification of patellofemoral osteoarthritis (PFOA) by computed tomography images or radiographs. The intraclass correlation coefficient (ICC) of each measurement, the correlations and differences among the parameters, and binary logistic regression analysis were conducted.

RESULTS

Each group in this study included 75 knees. The inter-observer and intra-observer reliability of the TT-TG distance decreased with the increasing degree of PFOA (ICC < 0.75). The reliability of the TT-RA distance showed excellent agreement in different stages of Iwano's classification. The HKA angle was poorly correlated with the TT-TG distance (r = 0.34, p = 0.003) and the TT-RA distance (r = 0.39, p = 0.001) in valgus knees. As the HKA angle increased by 1 degree, the TT-TG and TT-RA distance increased by nearly 0.45 mm and 0.61 mm, respectively. Valgus malalignment and severe PFOA revealed significant ORs of 3.26 (95% CI [1.06-10.03], p = 0.036) and 3.10 (95% CI [1.01-9.54], p = 0.048) with regard to pathological TT-RA distance, respectively.

CONCLUSION

The TT-RA distance was more reliable than the TT-TG distance in patients with knee osteoarthritis. Valgus malalignment and severe PFOA were risk factors for pathological TT-RA distance.

KEY POINTS

• The TT-RA distance is a reliable and repeatable alternative to the TT-TG distance in evaluating coronal malalignment, especially in patients with severe PFOA. • We validated the significant relationships between TT-TG distance or TT-RA distance and HKA angle in valgus knees, while the correlations among such parameters were not significant in varus knees. • Pathological lateralization of the tibial tubercle was prone to be traced in patients with valgus malalignment or severe PFOA, which could contribute to the patellofemoral malalignment.

Influence of Articular Geometry and Tibial Tubercle Location on Patellofemoral Kinematics and Contact Mechanics

Trochlear groove geometry and the location of the tibial tubercle, where the patellar tendon inserts, have both been associated with patellofemoral instability and can be modified surgically. Although their effects on patellofemoral biomechanics have been investigated individually, the interaction between the two is unclear. The authors' aim was to use statistical shape modeling and musculoskeletal simulation to examine the effect of patellofemoral geometry on the relationship between tibial tubercle location and patellofemoral function. A statistical shape model was used to generate new knee geometries with trochlear grooves ranging from shallow to deep. A Monte Carlo approach was used to create 750 knee models by randomly selecting a geometry and randomly translating the tibial tubercle medially/laterally and anteriorly. Each knee model was incorporated into a musculoskeletal model, and an overground walking trial was simulated. Knees with shallow trochlear geometry were more sensitive to tubercle medialization with greater changes in lateral patella position (-3.0 mm/cm medialization shallow vs -0.6 mm/cm deep) and cartilage contact pressure (-0.51 MPa/cm medialization shallow vs 0.04 MPa/cm deep). However, knees with deep trochlear geometry experienced greater increases in medial cartilage contact pressure with medialization. This modeling framework has the potential to aid in surgical decision making.

Sonographic evaluation of patellar tendon displacement and its correlation with patellofemoral pain syndrome

Background

Patellofemoral pain syndrome is the most common knee condition and is associated with patellar maltracking. Ultrasound is used in studying patellar maltracking. The objective is to determine if the technique which analyzes the displacement of the patellar tendon in the trochlear sulcus is associated with patellofemoral pain syndrome.

Methods

In total, 68 knees of 34 football players (males = 20, females = 14) were included. Patellar tendon displacement was assessed in supine and standing positions. Patellar tendon displacement difference in the two positions was determined.

Results

There was a significant difference in the lateral patellar tendon displacement during standing which was larger in patellofemoral pain syndrome than without patellofemoral pain syndrome (Mean Rank = 39.20 vs. 30.32, p = 0.02). There was no significant difference between the two groups for lateral patellar tendon displacement in supine and the difference in patellar tendon displacement from supine to standing.

Conclusion

The technique could be a potential method in assessing patellar maltracking. It could be used to have a comprehensive understanding of the pathomechanics and treatment of patellofemoral pain syndrome.

Ipsilateral patellofemoral morphological abnormalities are more severe than those of contralateral joints in patients with unilateral patellar dislocation

PURPOSE

To determine the differences in anatomic parameters between ipsilateral dislocated knees and contralateral non-dislocated knees in patients with unilateral patellar dislocation and to identify any variations in ipsilateral knees contributing to contralateral anatomic abnormalities.

METHODS

A total of 82 patients with unilateral patellar dislocation from 2016 to 2019 were retrospectively evaluated. Bilateral anatomic factors, including the tibial tubercle to trochlear groove (TT-TG) distance, lower limb rotational deformities, trochlear dysplasia, patella tilt, and patellar height, were assessed by CT.

RESULTS

The study included 46 patients (32 females and 14 males, mean age ± SD 20.5 ± 6.8). The interobserver reliability of each parameter showed excellent agreement. The ipsilateral TT-TG distance (P = 0.004), patella tilt (P = 0.001), and patellar height (P = 0.01) were greater in the ipsilateral knees than in the contralateral knees. The lateral trochlea inclination (LTI) in the contralateral knees was larger than that in the ipsilateral knees (P = 0.022). There was a significant difference in the distribution of trochlear dysplasia of Dejour between the ipsilateral knees (dislocated side) and the contralateral knees (P = 0.036). However, bilateral femoral and/or tibial torsion, and bilateral knee joint rotation did not differ significantly. Binary logistic regression showed that only ipsilateral LTI revealed significant ORs of 8.83 (P = 0.016) and 7.64 (P = 0.018) with regard to contralateral abnormal tibial torsion and LTI, respectively.

CONCLUSION

In patients with unilateral patellar dislocation, the ipsilateral TT-TG distance, patella tilt, and patellar height values were larger in the ipsilateral knees than in the contralateral knees, and trochlear dysplasia was more severe in the ipsilateral joints. The risks of contralateral pathological tibial torsion and LTI were 8.8- and 7.6-fold higher, respectively, in patients with abnormal ipsilateral LTI.

LEVEL OF EVIDENCE

Level IV.

A robust and semi-automatic quantitative measurement of patellofemoral instability based on four dimensional computed tomography

Patellofemoral instability is a motion related disease, featured as the patella dislocating from the trochlear groove. Four dimensional computed tomography (4DCT) enables full assessment of the patellofemoral movement. Nevertheless, the quantitative measurements of patellofemoral instability are still under research and currently of limited practical use. The aim of this study is to develop a robust and semi-automatic workflow to quantitatively describe the patellofemoral movement in a patient group of eight suffering from patellofemoral instability. The initial results show agreement with manual observations of the tibial tubercle - trochlear groove (TT-TG) distance in routine practice, and the possibility to evaluate both TT-TG distance and patellar centre - trochlear groove (PC-TG) distance dynamically during active flexion-extension-flexion movement of the knee.

Unilateral anterior knee pain is associated with increased patellar lateral position after stressed lateral translation

PURPOSE

To objectively compare side-to-side patellar position and mobility in patients with idiopathic unilateral anterior knee pain (AKP) using a stress-testing device concomitantly with magnetic resonance imaging. It is hypothesized that the painful knees present greater patellar mobility than the contralateral non-painful knees.

METHODS

From a total sample of 359 patients, 23 patients with idiopathic unilateral AKP (30.9 years, 23.4 kg/m², 43% males) were included within the present study. Both knees of all the patients were examined by conventional imaging, including the measurement of trochlear sulcus angle, Caton-Deschamps index, tibial tuberosity to trochlear groove distance, patellar tilt angle and patellar subluxation (both at rest and upon quadriceps contraction). Additionally, the same patients underwent stress testing (Porto Patella Testing Device); these measurements were taken with the patella at rest, after lateral patellar translation and after lateral patellar tilt. Clinical and functional outcomes were obtained using physical examination and the Kujala and Lysholm scores.

RESULTS

Painful knees showed statistically significant higher patellar lateral position after stressed lateral translation than non-painful knees (p = 0.028), 9.8 ± 3.6 mm and 7.1 ± 6.3 mm, respectively. The adjusted multivariate logistic model identified the patellar position after lateral displacement to be significantly associated with AKP (OR = 1.165) and the model (AUC = 0.807, p < 0.001) showed reasonable sensitivity (67%) and specificity (73%).

CONCLUSION

Patients with idiopathic unilateral AKP with morphologically equivalent knees showed statistically significant increased patellar lateral position after stressed lateral displacement in their painful knee. The greater lateral patellar mobility quantified by the PPTD testing brings more objectivity to the diagnosis.

LEVEL OF EVIDENCE

II.

Does Preoperative tibial tuberosity: Trochlear groove distance effect on postoperative patellar instability in the patients with knee arthroplasty due to medium-advanced knee osteoarthritis?

Objectives: Determining tibial tubercle-trochlear groove distance range as measured before the operation in the patients to whom total knee prosthesis will be applied due to mid to advanced level of osteoarthritic and seeing the post-operative variations in tibial tubercle-trochlear groove distance and evaluating whether it has any impact on the patellofemoral instability that might develop after the operation. 46 knees planned to be applied total knee prosthesis due to mid-advanced level of osteoarthritic were examined. Methods: In the preoperative and postoperative magnetic resonance images MRI routinely taken, tibial tubercle-trochlear groove distance was measured. Later it was examined whether there was correlation between these preoperative and postoperative tibial tubercle-trochlear groove measurements and the data recorded before operation. Results: Preoperative tibial tubercle-trochlear groove distance was found to be 8.83 ± 3.54, postoperative tibial tubercle-trochlear groovedistance was found to be 8.30 ± 3.89 and preoperative-postoperative tibial tubercle-trochlear groove variation was found to be 0,52 ± 3,64 (p = 0,337). In the patients whose alignment was 10 degrees or less, Pre-Op tibial tubercle-trochlear groove distance was measured as 8.74 ± 3.18 and in the patients whose alignment was more than 10 degrees, it was measured as 8.89 ± 3,83 (p = 0.888). In the patients whose alignment was 10 degrees or less, Post-Op tibial tubercle-trochlear groove distance was measured as 8.00 ± 2.85 and in the patients whose alignment was more than 10 degrees, it was measured as 8.52 ± 4.52 (p = 0.661). In the patients whose alignment was 10 degrees or less, tibial tubercle-trochlear groove distance variation was measured as 0.74 ± 3.25 and in the patients whose alignment was more than 10 degrees, it was measured as 0.37 ± 3.95 (p = 0.741). Coclusion: As a result, although tibial tubercle-trochlear groove distance was observed with a great variation in the osteoarthritic knees at stage 3-4, it was nonetheless measured within normal limits and Post-Op variation was not meaningful. Since this is the first study in the literature on the measurement of tibial tubercle-trochlear groove distance in the total knee prosthesis applications, we hope that it would shed some light on similar studies to be conducted in the future.

Patellofemoral Pain

Patellofemoral pain (PFP) is a common musculoskeletal-related condition that is characterized by insidious onset of poorly defined pain, localized to the anterior retropatellar and/or peripatellar region of the knee. The onset of symptoms can be slow or acutely develop with a worsening of pain accompanying lower-limb loading activities (eg, squatting, prolonged sitting, ascending/descending stairs, jumping, or running). Symptoms can restrict participation in physical activity, sports, and work, as well as recur and persist for years. This clinical practice guideline will allow physical therapists and other rehabilitation specialists to stay up to date with evolving PFP knowledge and practices, and help them to make evidence-based treatment decisions. J Orthop Sports Phys Ther. 2019;49(9):CPG1-CPG95. doi:10.2519/jospt.2019.0302.

Anatomic Risk Factors for Focal Cartilage Lesions in the Patella and Trochlea: A Case-Control Study

BACKGROUND

Focal cartilage lesions in the patellofemoral (PF) joint are common. Several studies correlated PF risk factors with PF instability, anterior knee pain, and PF arthritis; however, there is a lack of evidence correlating those factors to PF focal cartilage lesions.

PURPOSE

To evaluate the influence of the anatomic PF risk factors in patients with isolated focal PF cartilage lesions.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Patients with isolated PF focal cartilage lesions were included in the cartilage lesion group, and patients with other pathologies and normal PF cartilage were included in the control group. Multiple PF risk factors were accessed on magnetic resonance imaging scans: patellar morphology (patellar width, patellar thickness, and patellar angle), trochlear morphology (trochlear sulcus angle, lateral condyle index, and trochlear sulcus depth), patellar height (Insall-Salvati ratio and Caton-Deschamps index), axial patellar positioning (patellar tilt, angle of Fulkerson), and quadriceps vector (tibial tuberosity-trochlear groove distance).

RESULTS

A total of 135 patients were included in the cartilage lesion group and 100 in the control group. As compared with the control group, the cartilage lesion group had a higher sulcus angle (P = .0007), lower trochlear sulcus depth (P < .0001), lower angle of Fulkerson (P < .0001), lower patellar width (P = .0003), and higher Insall-Salvati ratio (P < .0001). From the patients in the cartilage lesion group, 36% had trochlear dysplasia; 27.6%, patella alta; and 24.7%, abnormal patellar tilt. These parameters were more frequent in the cartilage lesion group (P < .0001). Trochlear lesions were more frequent in men, presented at an older age, and had fewer associated anatomic risk factors. Patellar lesions, conversely, were more frequent in women, presented at younger age, and were more closely associated with anatomic risk factors.

CONCLUSION

PF anatomic abnormalities are significantly more common in patients with full-thickness PF cartilage lesions. Trochlear dysplasia, patella alta, and excessive lateral patellar tilt are the most common correlated factors, especially in patellar lesions.

Highly variable tibial tubercle-trochlear groove distance (TT-TG) in osteoarthritic knees should be considered when performing TKA

PURPOSE

The tibial tubercle-trochlear groove distance (TT-TG) is an established measurement to assist diagnosis and treatment of patellofemoral instability. However, little is known about the distribution of TT-TG in osteoarthritic knees. The purpose of the current study is to investigate the TT-TG in a large cohort of osteoarthritic knees and to analyse, in particular, the association of knee alignment and TT-TG.

METHODS

Data from 962 consecutive patients [455 male, 507 female; mean age ± SD 70.8 ± 9.3 (37-96)] who had undergone 3D-CT and preoperative knee planning with validated commercial 3D planning software before total knee arthroplasty (TKA) were collected prospectively. The TT-TG, coronal hip knee ankle angle (HKA), femoral anteversion (AVF), external tibial torsion (ETT), and femorotibial rotation (Rot FT) were analysed. Pearson correlations were performed to assess correlations between TT-TG, mechanical axis, and rotational parameters (p < 0.05).

RESULTS

HKA showed a strong correlation with TT-TG (r = 0.488; p < 0.001) with 98 (67.1%) and 45 (30.8%) of valgus knees having respective abnormal and pathological TT-TG values. There were no significant correlations between parameters of rotational alignment (AVF, ETT, Rot FT) and TT-TG. Mean TT-TG was 12.9 ± 5.6 mm, ranging from 0.0 to 33.7 mm. 325 (33.8%) of all patients had abnormal (> 15 mm) and 101 (10.5%) had pathological (> 20 mm) values. A varus alignment was present in 716 (74.4%) of the cases (HKA < - 1.5°), a neutral alignment in 100 (10.4%), and a valgus alignment in 146 (15.2%) (HKA > 1.5°).

CONCLUSION

A wide variation of TT-TG values in osteoarthritic knees was shown by our results. There was a relevant influence of coronal limb alignment on the TT-TG-the more valgus the higher and more pathological the TT-TG. With the aim of having a more personalised TKA, the individual TT-TG should be taken into account to improve the outcome.

LEVEL OF CLINICAL EVIDENCE

III. Retrospective cohort study.

Return to Sports After Tibial Tubercle Osteotomy for Patellofemoral Pain and Osteoarthritis

PURPOSE

To determine the rate of return to sports and clinical outcomes after anteromedialization (AMZ) tibial tubercle osteotomy (TTO) for patients with patellofemoral pain and/or osteoarthritis.

METHODS

This study is a retrospective case series of consecutive patients who underwent unilateral or staged bilateral AMZ TTO for a primary diagnosis of patellofemoral pain or arthritis. Included were all patients with minimum 1-year follow-up. The indication for surgery was failure of at least 6 months of nonoperative treatment. Simultaneous tubercle distalization or proximal-medial soft-tissue procedures were excluded; however, prior patellar instability procedures did not prohibit inclusion if there was no recurrence. A diagnostic arthroscopy was performed to evaluate the cartilage surfaces; AMZ TTO was performed by use of a freehand technique and two 4.5-mm fully threaded screws for fixation. A gradual return to activities was permitted at 6 months; however, contact sports were prohibited until 9 months postoperatively. Patients were evaluated retrospectively for participation in sports using a questionnaire about the level of participation, return to sporting activities, and Kujala score. Statistical analysis included 1-way analysis of variance and χ² or Fisher exact and paired t tests.

RESULTS

Forty-eight patients played sports within 3 years before surgery. The majority were female patients (84.2%). The average age at surgery was 29.6 years, with an average follow-up period of 4.6 years. The average Kujala score improved from 51.2 to 82.6 (P < .0001); the average pain score improved from 4.1 to 1.8 (P < .001). Of the patients, 83.3% returned to at least 1 sport on average 7.8 months postoperatively. Of these, 77.5% believed they returned to sports at the same level or a higher level.

CONCLUSIONS

Patients undergoing AMZ TTO for patellofemoral pain or arthritis had an 83.3% rate of return to 1 or more sporting activities at an average of 7.8 months after surgery, with many patients returning at the same level or a higher level of intensity compared with their preoperative state.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

The Relationship of Static Tibial Tubercle-Trochlear Groove Measurement and Dynamic Patellar Tracking

BACKGROUND

The tibial tubercle to trochlear groove (TT-TG) distance is used for screening patients with a variety of patellofemoral joint disorders to determine who may benefit from patellar medialization using a tibial tubercle osteotomy. Clinically, the TT-TG distance is predominately based on static imaging with the knee in full extension; however, the predictive ability of this measure for dynamic patellar tracking patterns is unknown.

PURPOSE

To determine whether the static TT-TG distance can predict dynamic lateral displacement of the patella.

STUDY DESIGN

Cohort study (Diagnosis); Level of evidence, 2.

METHODS

The static TT-TG distance was measured at full extension for 70 skeletally mature subjects with (n = 32) and without (n = 38) patellofemoral pain. The dynamic patellar tracking patterns were assessed from approximately 45° to 0° of knee flexion by use of dynamic cine-phase contrast magnetic resonance imaging. For each subject, the value of dynamic lateral tracking corresponding to the exact knee angle measured in the static images for that subject was identified. Linear regression analysis determined the predictive ability of static TT-TG distance for dynamic patellar lateral displacement for each cohort.

RESULTS

The static TT-TG distance measured with the knee in full extension cannot accurately predict dynamic lateral displacement of the patella. There was weak predictive ability among subjects with patellofemoral pain ( r² = 0.18, P = .02) and no predictive capability among controls. Among subjects with patellofemoral pain and static TT-TG distances 15 mm or more, 8 of 13 subjects (62%) demonstrated neutral or medial patellar tracking patterns.

CONCLUSION

The static TT-TG distance cannot accurately predict dynamic lateral displacement of the patella. A large percentage of patients with patellofemoral pain and pathologically large TT-TG distances may have neutral to medial maltracking patterns.