Patellar Malalignment Research Articles

The Measurement of Patellar Alignment in Patellofemoral Pain Syndrome: Are We Confusing Assumptions With Evidence?

Patellofemoral pain syndrome is one of the most common orthopaedic complaints presenting to physical therapists. Although its etiology is uncertain, the cause is most often considered to be malalignment or lateral tracking of the patella. Consequently, measurement of patellar alignment has come to be accepted as an integral part of the examination of patellofemoral pain syndrome. Various measurement techniques exist, both clinical and radiological, and these have been frequently used in the diagnosis and treatment of the condition. As a corollary, the widespread use of such measurements has also lent weight to the theory that patellar malalignment is one of the primary causes of patellofemorai pain syndrome. However, an analysis of the literature reveals that the vast majority of these measurement procedures lack the appropriate scientific qualities to be considered acceptable measurement tools, including questionable reliability and validity, and an absence of appropriate normative data and a gold standard. This paper assesses the evidence for the usefulness of the most commonly used measures of patellar alignment and concludes that many of the beliefs of the clinical community with regard to the existence and measurement of patellar malalignment in patellofemoral pain syndrome may be based largely on assumptions and not on evidence.

Patellar malalignment is associated with radiographic features of knee OA

Patellar malalignment is associated with radiographic features of knee OA

Patella malalignment, pain and patellofemoral progression: the Health ABC Study

Patellofemoral (PF) joint osteoarthritis (OA) is strongly correlated with lower extremity disability and knee pain. Risk factors for pain and structural progression in PF OA are poorly understood. Our objective was to determine the association between patella malalignment and its relation to pain severity, and PF OA disease progression. We conducted an analysis of data from the Health ABC knee OA study. Health ABC is a community based, multi-center cohort study of 3075 Caucasian and Black men and women aged 70-79 at enrollment. Weight bearing skyline knee X-rays were obtained in a subset (595) of subjects, with and without knee pain, at year 2 and year 5 (mean follow-up 36 months). Films were read paired, and PF osteophytes (OST) and joint space narrowing (JSN) were scored on a 0-3 scale using the Osteoarthritis Research Society International atlas. We defined progression of PF OA as any increase in JSN score. Three measures of patella malalignment were made: sulcus angle; patella tilt angle; and patella subluxation medially or laterally (bisect offset). Knee symptoms were assessed using a knee specific Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) knee pain subscale. We assessed the relationship between baseline patella malalignment and pain severity (linear regression for WOMAC) and compartment specific PF OA progression (logistic regression for dichotomous outcomes). We classified continuous measures of patella alignment into quartile groups. We performed multivariable adjusted logistic regression models, including age, gender and body mass index (BMI) to assess the relation of baseline patella alignment to the occurrence of PF JSN progression using generalized estimating equations (GEE). The subjects had a mean age 73.6 (SD 2.9), BMI 28.8 (SD 4.9), 40.3% male, and 46% were Black. Medial displacement of the patella predisposed to medial JSN progression; odds for each quartile 1, 1.2, 1.2, 2.2 (P for trend=0.03), whilst protecting from lateral JSN progression; odds for each quartile 1, 0.7, 0.6, 0.4 (P for trend=0.0004). Increasing patella tilt protected from medial JSN progression; odds for each quartile 1, 0.8, 0.5, 0.2 (P<0.0001) and trended to increasing pain severity (P=0.09). Patella malalignment is associated with PF disease progression. Medial displacement and tilt of the patella predisposes to medial JSN progression, whilst lateral displacement is predictive of lateral JSN progression. The influence of patella malalignment has important implications since it is potentially modifiable through footwear, taping and/or knee bracing.

A new CT scan method for measuring the tibial tubercle trochlear groove distance in patellar instability

Patellar malalignment leading to objective or potential patella instability can be caused by tibial tuberosity lateralisation. This can be treated with a tuberosity medialisation. CT scan measurements are needed to assess the tibial tubercle trochlear groove distance. When using the previously described methods to determine this distance it can be difficult to determine the anatomical structures on the maximum intensity projection images, and this can lead to measurement error. This study was designed to compare the reliability of a new computer based CT measurement to the previously described method to determine the tibial tubercle trochlear groove distance. For each method, four observers measured each of 50 knees twice. The inter- and intra-observer variability for the conventional method and a new method were determined. Using the conventional method, the number of knees for which the difference between the aggregate mean of all eight measurements and the mean of duplicate measurements per observer greater than 2mm varied among the observers between 7 and 24 for the 50 knees, while this variation between four and seven for the same 50 knees using the new method. The limits of reproducibility based on measurements from the four different observers improved by 25%, indicating that the measurement error is considerably smaller with the new method. We advise using this more accurate method to improve the selection of patients for a tuberosity medialisation.

Patellofemoral Joint Kinematics in Individuals with and without Patellofemoral Pain Syndrome

Patellofemoral pain syndrome is a prevalent condition in young people. While it is widely believed that abnormal patellar tracking plays a role in the development of patellofemoral pain syndrome, this link has not been established. The purpose of this cross-sectional case-control study was to test the hypothesis that patterns of patellar spin, tilt, and lateral translation make it possible to distinguish individuals with patellofemoral pain syndrome and clinical evidence of patellar malalignment from those with patellofemoral pain syndrome and no clinical evidence of malalignment and from individuals with no knee problems. Three-dimensional patellofemoral joint kinematics in one knee of each of sixty volunteers (twenty in each group described above) were assessed with use of a new, validated magnetic resonance imaging-based method. Static low-resolution scans of the loaded knee were acquired at five different angles of knee flexion (ranging between -4 degrees and 60 degrees). High-resolution geometric models of the patella, femur, and tibia and associated coordinate axes were registered to the bone positions on the low-resolution scans to determine the patellar motion as a function of knee flexion angle. Hierarchical modeling was used to identify group differences in patterns of patellar spin, tilt, and lateral translation. No differences in the overall pattern of patellar motion were observed among groups (p>0.08 for all global maximum likelihood ratio tests). Features of patellar spin and tilt patterns varied greatly between subjects across all three groups, and no significant group differences were detected. At 19 degrees of knee flexion, the patellae in the group with patellofemoral pain and clinical evidence of malalignment were positioned an average of 2.25 mm more laterally than the patellae in the control group, and this difference was marginally significant (p=0.049). Other features of the pattern of lateral translation did not differ, and large overlaps in values were observed across all groups. It cannot be determined from our cross-sectional study whether the more lateral position of the patella in the group with clinical evidence of malalignment preceded or followed the onset of symptoms. It is clear from the data that an individual with patellofemoral pain syndrome cannot be distinguished from a control subject by examining patterns of spin, tilt, or lateral translation of the patella, even when clinical evidence of mechanical abnormality was observed.

Efekti sekcije lateralnih retinakula kolena u operativnom lecenju simptomatske patelofemoralne inkongruencije

Biomechanical malfunction of the knee extensor mechanism in the patello femoral joint is regarded as patella malalignment but major patients complaints are anterior knee pain and patellar slipping. Lateral retinacular release is one of the basic surgical procedures in the treatment of patellar malalignment. The aim of the study was to estimate the achievements of the lateral retinacular release in solving particular biomechanical disorders of the patello femoral joint, as well as individual patients complaints. Evaluation of objective parameters x-ray and clinical findings before and after the operation, shows statistically highly significant difference, thus confirming implementation of the fore mentioned surgical procedure. Despite the fact that anterior knee pain subsided postoperatively in the number of patients, statistically significant values, comparing to the preoperative findings, could not be obtained. Incidence of the patellar slipping has shown statistically significant reduction two years following the surgery. Achieving proper biomechanical alignment of the patello femoral joint is obviously not sufficient to provide relief of subjective complaints, especially concerning anterior knee pain, although considerable improvements were registered in the number of patients.

Relationship of Q angle and joint hypermobility and Q angle values in different positions

Patellar malalignment is the most important reason for anterior knee pain. Patellar alignment is commonly determined by the measurement of the quadriceps (Q) angle. In this study, our primary aim was to investigate the Q angle difference between healthy individuals with and without joint hypermobility. The other objectives were to compare the Q angle values, which were measured in supine and upright positions, to determine hypermobility frequency among healthy males in a certain population, and to investigate the correlation between the existent skeletal deformities and Beighton score levels. Two hundred fifty-three healthy male college students were examined for hypermobility and skeletal deformities. According to the Beighton scoring system, three groups (n=20) were formed, and Q angle measurements were performed on the 60 individuals in both supine and upright positions. In the comparison of the groups, the mean Q angle values in healthy hypermobile individuals were found to be significantly higher than that of the nonhypermobile ones (p<0.05). No statistical difference was found between Q angle values in supine and upright positions (p>0.05). The frequency of joint hypermobility (Beighton score 4 or more) was found to be 29.25% in this population. No correlation was determined between existent skeletal deformities and Beighton score values (p>0.05). In conclusion, the Q angle evaluation among healthy hypermobile individuals may have a prognostic value for probable knee pathologies that may appear in the future.

Patellar polyethylene peg fracture: a case report and review of the literature

The patellar component of a total knee replacement (TKR) is the most frequent source of non-septic complications after total knee arthroplasty. Fracture of patellar pegs in all polyethylene patellar components is a very rare occurrence. We report such a case of a patellar polyethylene fracture in a 72-year-old female patient 10 years after TKR. Due to patellar malalignment and high level of activity, the patellar components failed in this patient. This was treated arthroscopically by removing the components that failed and leaving the patella unresurfaced. We followed up the patient postoperatively and her symptoms were substantially resolved.

Patellofemoral Arthroplasty

Patellofemoral arthroplasty is a worthy alternative to total knee arthroplasty or patellectomy in patients with arthritis localized to the anterior compartment of the knee, particularly when there is no considerable patellar malalignment or maltracking. The results can be optimized by accurately aligning the prosthesis and balancing the soft tissues to enhance patellar tracking. However, some designs are particularly vulnerable to patellofemoral complications. Postoperative patellofemoral dysfunction should be reduced by using a trochlear component that engages the patella within the trochlear groove and articulates with the patella completely in extension, but which is relatively unconstrained in extension and has a sagittal radius of curvature that fits well with the native distal femur. The incidence of patellofemoral complications was reduced in my series from 17% with a first generation implant to 4% with a second generation implant. Evolving designs likely will eliminate many of the complications of early generation implants, leaving tibiofemoral degeneration the major source of failure of patellofemoral arthroplasties.

Factors affecting the outcome of distal realignment for patellofemoral disorders of the knee

This study correlated the risk factors with the clinical outcome of distal realignment for patellofemoral disorders in 48 patients with 53 knees with 25 to 96 months follow-up. The indications for surgery included pain and disability due to patellofemoral disorders with failure of at least 6 months of conservative treatments. The evaluations included pain scores, Lysholm functional scores and radiographs of the knee. The overall results were satisfactory in 47 knees (88.7%) and unsatisfactory in six knees (11.3%). There was no correlation of the clinical results with age, sex, body weight and body height, preoperative pain scores and Lysholm scores. However, the clinical outcome correlated with the severity of articular damage and the correction of patellar malalignment. Error in patient selection and inadequate surgical technique were attributable to poor outcomes.

In vivo and Noninvasive Load Sharing among the Vasti in Patellar Malalignment

It is not clear how the knee extension torque is distributed quantitatively among the lateral and medial vasti in patellofemoral pain (PFP) patients with patellar malalignment, which was investigated in vivo and noninvasively in ten PFP patients and eleven controls. We hypothesized that the vastus medialis oblique (VMO) and vastus medialis longus (VML) of PFP patients contribute less to knee extension than that in controls. Electrical stimulation was used to activate each vastus component selectively. The relationship between the knee extension torque generated by each individual vastus component and the corresponding compound muscle action potential (M-wave) was established over different contraction levels, which was used to calibrate the corresponding voluntary EMG signal and determine torque ratios of VMO/VL (vastus lateralis), VMO/VML, VML/VL and (VMO+VML)NL during voluntary isometric knee extension. The VMO and VML of PFP patients contributed significantly less to knee extension than their counterparts in controls. The combination of VMO and VML generated comparable amount of extension torque as the VL in the controls, while it produced significantly lower extension torque than that of the VL in the PFP patients. In addition, the VMO/VL was lower than VMO/VML and VML/VL in both PFP and control groups. Compared to controls, the VMO and VML in the PFP patients contributed significantly less to the knee extension torque. The approach can be used to investigate load sharing among quadriceps muscles in vivo and noninvasively, in both healthy subjects and patients with patellofemoral disorder and patellar malalignment.

Treatment of full thickness chondral lesions of the knee with microfracture in a group of athletes

This prospective outcomes study was designed to prospectively investigate the outcome of the microfracture technique when applied to full thickness chondral lesions of the knee in a group of athletes. From 1991 to 1999, 109 patients were treated using the microfracture technique. We prospectively followed up 53 athletes who satisfied our inclusion criteria. Average age was 38 years (range 19-55) and mean follow-up was 72 months (range 36-120). Etiology, clinical signs, symptoms and activity level were noted preoperatively and at final follow-up. Lysholm, Tegner, IKDC and functional tests were utilized. Intraoperatively, location, size of the lesions and associated pathologies were recorded. Roentgenograms, MRI or CT scan were done before treatment and at final follow-up. Etiologic factors were mostly related to sports microtrauma (37.5%) and macrotrauma (21%), while 37.5% of our patients did not report any traumatic etiology and 4% showed patellar malalignment. The most common location was medial femoral condyle (61%). Knee pain and swelling improved in 70%, tibiofemoral crepitus in 60%. Hop test was normal in 70% at final follow-up. Subjective evaluation was 40/100 preoperatively and 70/100 at final follow-up. Lysholm was 56.8 preoperatively and 87.2 final. IKDC revealed: 0 A, 3 B, 40 C and 10 D preoperatively while at final follow-up 70% scored A or B. Tegner improved at 2 years from 3.2 to 6; however, at final follow-up 80% showed a decline in sport activity level (Tegner 5). Microfracture technique can offer clinical, functional and subjective improvement in athletically active patients. However because of the decline in sports participation over time, microfracture may not be the definitive procedure for the athlete's knee and other procedures may be indicated in the future.

The influence of iliotibial tract on patellar tracking.

Thirty patients with 49 snapping hips and patellar malalignment underwent surgical release of the iliotibial tract contracture over the trochanteric area. Minimal follow-up was 2 years (average 4.6 years, range: 2-9 years). Eight patients underwent computed tomography (CT) preoperatively and 1 month postoperatively to investigate the patellar location in the patellofemoral articulation with knee bending at 0 degrees, 20 degrees, 45 degrees, 60 degrees, and 90 degrees. Significant improvements in the congruence angle and lateral patellofemoral angle were noted on Merchant radiograph for all knees (P<.01). On CT, at 20 degrees and 45 degrees knee bending, all congruence, lateral patellofemoral, and patellar tilt angles significantly improved postoperatively in 8 knees (P<.01). Iliotibial tract affects patellar tracking and dominates lateral patellar supporting structures.

In vivo and noninvasive three-dimensional patellar tracking induced by individual heads of quadriceps.

Unbalanced actions of the quadriceps components are closely linked to patellar mal-tracking and patellofemoral pain syndrome. However, it is not clear how individual quadriceps components pull and rotate the patella three dimensionally. The purpose of this study was to investigate in vivo and noninvasively patellar tracking induced by individual quadriceps components. Individual quadriceps component was activated selectively through electrical stimulation at the muscle motor point, and the resulting patellar tracking was measured in vivo and noninvasively in 18 knees of 12 subjects. The in vivo and noninvasively patellar tracking was corroborated with in vivo fluoroscopy and in vitro cadaver measurements. Vastus medialis (VM) mainly pulled the patella first in the medial and second in the proximal directions and vastus lateralis (VL) pulled first in the proximal and second in the lateral directions. The oblique portion (VMO) of the VM pulled the patella mainly medially and the longus portion (VML) more proximally. Medial tilt was the major patellar rotation induced by VMO contraction at full knee extension. With the knee at the more flexed positions, the amplitude of patellar movement induced by comparable quadriceps contractions was reduced significantly compared to that at full knee extension, and VMO changed its main action from extending to flexing the patella. The medial and lateral quadriceps components moved the patella in rather different directions, and rotated the patella differently about the mediolateral tilt and mediolateral rotation axes but similarly in extension. The approach can be used to investigate patellar tracking in vivo and noninvasively in both healthy subjects and patients with patellofemoral disorder and patellar malalignment.

A noninvasive magnetic resonance imaging-based method for assessing patellofemoral joint kinematics detects differences between healthy and symptomatic knees

Patellofemoral joint pain is one of the most common pathologies observed in orthopedic clinics. It is widely held that abnormal joint mechanics play a causative role in the development of anterior knee pain and that chronic patellofemoral joint pain may lead to cartilage degeneration, arthritis and permanent disability [1]. However, the relationship between joint kinematics and clinical symptoms remains unclear. We applied a new magnetic resonance imaging (MRI)-based method to assess three-dimensional patellar tracking during loaded knee flexion to determine whether anterior knee pain is associated with abnormal joint kinematics. The symptomatic and matched knees of 60 subjects (20 cases with anterior knee pain and clinical evidence of patellar malalignment; 20 cases with anterior knee pain and no clinical evidence of patellar malalignment, and 20 controls matched for age, gender and physical activity level) were imaged through a range of loaded knee flexion using a validated MRI-based method [2]. Using this novel evaluation tool, the motion of the patella relative to the femur was determined as a function of knee flexion angle. Group values through a common range of knee flexion were compared using analysis of variance. In the control group, the normal pattern of patellar motion is increasing medial rotation, tilt and shift as the patella approaches the trochlear groove during loaded knee flexion (from 19° to 28°). In the group with pain and clinical signs of malalignment, the patella is translated 2.6 mm more laterally and rotated 1.3° more medially (P < 0.001). Statistically, differences in patellar kinematics are observed between the control group and the group with pain and no clinical evidence of malalignment; however, the magnitude of the differences are all within the range of the accuracy and repeatability of the technique with the exception of the decreased distance between the patella and femur (P < 0.001). This MRI-based method detects a normal pattern of patellar kinematics that is consistent with previous reports [3] and detects abnormal kinematics in subgroups of individuals with anterior knee pain. In the cases with pain and clinical evidence of patellar malalignment, the increased lateral shift and medial rotation is consistent with weakness of the vastus medialis oblique muscle, which has been linked with patellofemoral joint pain previously. Our results do not support the notion that increased lateral tilt is associated with patellofemoral joint pain. In the cases with pain and no clinical evidence of patellar malalignment, the closer positioning of the patella relative to the femur may reflect a decrease in cartilage thickness. Of note is that in most cases the pattern of patellar motion was similar to that for the controls. Longitudinal studies using this novel MRI-based method will aid in determining the link between knee pain and joint mechanics.

The influence of altered lower-extremity kinematics on patellofemoral joint dysfunction: a theoretical perspective.

Although patellofemoral pain (PFP) is recognized as being one of the most common disorders of the lower extremity, treatment guidelines and underlying rationales remain vague and controversial. The premise behind most treatment approaches is that PFP is the result of abnormal patellar tracking and/or patellar malalignment. Given as such, interventions typically focus on the joint itself and have traditionally included strengthening the vastus medialis oblique, taping, bracing, soft tissue mobilization, and patellar mobilization. More recently, it has been recognized that the patellofemoral joint and, therefore, PFP may be influenced by the interaction of the segments and joints of the lower extremity. In particular, abnormal motion of the tibia and femur in the transverse and frontal planes may have an effect on patellofemoral joint mechanics. With this in mind, interventions aimed at controlling hip and pelvic motion (proximal stability) and ankle/foot motion (distal stability) may be warranted and should be considered when treating persons with patellofemoral joint dysfunction. The purpose of this paper is to provide a biomechanical overview of how altered lower-extremity mechanics may influence the patellofemoral joint. By addressing these factors, better long-term treatment success and prevention may be achieved.

In vivo and noninvasive six degrees of freedom patellar tracking during voluntary knee movement

Objective. The purpose of this study was to investigate in vivo and noninvasively patellar tracking in six degrees of freedom during voluntary knee extension and flexion. Design. Patellar tracking was evaluated in vivo and noninvasively with corroboration using in vivo fluoroscopy and in vitro cadaver measurements. Background. Patellofemoral pain is closely related to abnormal patellar tracking and malalignment. However, there is a lack of quantitative and convenient methods to evaluate six degrees of freedom in vivo patellar tracking, partly due to difficulty in evaluating 3-D patellar tracking noninvasively. Methods. Six degrees of freedom patellar tracking was measured in vivo and noninvasively using a small clamp mounted onto the patella and an optoelectronic motion capture system in 18 knees of 12 healthy subjects during voluntary knee extension and flexion. Results. The patella tracked systematically following a certain pattern during knee extension and flexion. Patellar tracking patterns during knee extension and flexion were not significantly different in the 18 knees tested. When the knee was voluntarily extended from 15° flexion to full extension, the patella was extended 8°, laterally tilted 2°, and shifted 3 mm laterally and 10 mm proximally. The results were consistent with previous in vitro and in vivo studies. Conclusions. Six degrees of freedom patellar tracking can be evaluated in vivo and noninvasively within the range of 20° flexion to full knee extension. Relevance The study provided us quantitative six degrees of freedom information about patellar tracking during knee flexion/extension, which can be used to investigate patellar tracking in vivo and noninvasively in both healthy subjects and patients with patellofemoral disorder and patellar malalignment.

Tibial tuberosity transfer, for patellar instability and malalignment: a new technique

Tibial tuberosity transfer, for patellar instability and malalignment: a new technique

Invited Commentary to: 'Arthroscopy of Total Knee Arthroplasties: Indications and Technical Problems' (Eur Surg 2002;34:309 - 311)

Background: Postoperative complaints after total knee arthroplasty range from restriction in range of motion, recurrent swelling, and soft tissue impingement through to prosthesis failure with no obvious radiological abnormality. This study looks at the indications and technical problems of arthroscopy in the treatment of symptomatic total knee arthroplasty. Methods: Fourteen arthroscopies were performed between 3 days and 10 years following total knee arthroplasty. Six of these cases presented significantly decreased range of motion, four had proximal medial joint line pain, two had pain with no obvious cause, one had a suspected patella incongruence with metal-back contact, and one case had a postoperative haemarthrosis. Results: Arthroscopy revealed adhesions and intra-articular fibrous bands resulting in incongruence of the patellofemoral joint and decreased range of motion. Medial compartment pain was due to pseudomeniscal hypertrophic villous synovium. In one case, the pain was due to chronic infection and open synovectomy was undertaken. A fracture of the polyethylene inlet was found by arthroscopy in one case. The suspected patella malalignment with metal-back contact was confirmed by arthroscopy. Technical problems encompassed mirror images, the possibility of damaging the components by arthroscopic manipulation, and the variants of prosthesis. Conclusions: Arthroscopy of total knee arthroplasties is a good minimally invasive method for the diagnosis and treatment of postoperative dysfunction, such as arthrofibrosis, soft tissue impingement, patella instability, infection, breakdown of implants and haemarthrosis.

Invited Commentary to:'Arthroscopy of Total Knee Arthroplasties: Indications and Technical Problems' (Eur Surg 2002;34:309 - 311)

Background: Postoperative complaints after total knee arthroplasty range from restriction in range of motion, recurrent swelling, and soft tissue impingement through to prosthesis failure with no obvious radiological abnormality. This study looks at the indications and technical problems of arthroscopy in the treatment of symptomatic total knee arthroplasty. Methods: Fourteen arthroscopies were performed between 3 days and 10 years following total knee arthroplasty. Six of these cases presented significantly decreased range of motion, four had proximal medial joint line pain, two had pain with no obvious cause, one had a suspected patella incongruence with metal-back contact, and one case had a postoperative haemarthrosis. Results: Arthroscopy revealed adhesions and intra-articular fibrous bands resulting in incongruence of the patellofemoral joint and decreased range of motion. Medial compartment pain was due to pseudomeniscal hypertrophic villous synovium. In one case, the pain was due to chronic infection and open synovectomy was undertaken. A fracture of the polyethylene inlet was found by arthroscopy in one case. The suspected patella malalignment with metal-back contact was confirmed by arthroscopy. Technical problems encompassed mirror images, the possibility of damaging the components by arthroscopic manipulation, and the variants of prosthesis. Conclusions: Arthroscopy of total knee arthroplasties is a good minimally invasive method for the diagnosis and treatment of postoperative dysfunction, such as arthrofibrosis, soft tissue impingement, patella instability, infection, breakdown of implants and haemarthrosis.