Patellar taping is a conservative treatment that may reduce patellar malalignment and pain in people with patellofemoral joint osteoarthritis (OA). This study aimed to compare patellar alignment in people with and without patellofemoral joint OA and to evaluate immediate effects of patellar taping on patellar alignment and pain in people with patellofemoral joint OA.
Patellar malalignment was measured from magnetic resonance imaging (MRI; 15° knee flexion) in 28 individuals (14 with patellofemoral joint OA and 14 asymptomatic, age-matched controls). In the patellofemoral joint OA group, MRI data were collected in 2 randomly allocated conditions (tape and no tape). Patellar alignment indices were measured from deidentified axial scans by 1 examiner. Pain during squatting was recorded in the 2 conditions (tape and no tape).
People with patellofemoral joint OA exhibited greater lateral displacement and bisect offset compared with controls (P < 0.001). Lateral patellar tilt angle did not differ between groups. In the patellofemoral joint OA group, patellar tape resulted in a significant lessening of lateral alignment, with reduced lateral displacement (P = 0.028) and increased lateral patellar tilt angle (P < 0.001). Mean pain during squatting decreased with patellar tape by 15 mm on a 100-mm scale (P = 0.045).
Patellar tape may reduce malalignment and pain associated with patellofemoral joint OA.
Osteoarthritis (OA) is a worldwide cause of pain and disability, with an estimated 27 million adults (age ≥45 years) in the US living with the disease (1). The knee joint is commonly affected by OA, resulting in pain and reduced function in activities of daily living, and frequently affecting quality of life. There is presently no cure for OA, and surgery is usually reserved for end-stage disease. Therefore, effective, readily available, and financially viable treatments are required to reduce the impact of OA on individuals and the community. Current clinical guidelines recommend tailoring knee OA treatments to the site of joint damage in order to optimize treatment outcomes (2, 3). The patellofemoral joint is one of the 3 knee joint compartments, and is frequently affected by the OA process (4, 5). Importantly, the pain and physical dysfunction of knee OA are often associated with structural damage in the patellofemoral joint (e.g., osteophytes, joint space narrowing [JSN], and reduced cartilage volume) (6–11). Presently, there are very few OA treatment strategies specifically targeting the patellofemoral joint, but patellar taping is one conservative intervention that has been recommended for treating patellofemoral joint OA (12).
Patellar taping is postulated to improve patellar alignment. The alignment of the patella within the femoral trochlea influences the magnitude and location of patellofemoral joint force (13–15). Although patellar malalignment is considered to be a feature of patellofemoral joint pain in younger populations (14, 15), no studies have investigated whether people with patellofemoral joint OA have malaligned patellae. However, recent research has identified that patellar malalignment is associated with indices of patellofemoral joint OA (JSN and loss of cartilage thickness) (16–18), increased risk of progression of OA (greater JSN) (19), and greater symptom severity (20, 21). Furthermore, patellar malalignment is typically observed in a lateral direction (displacement or tilt), which likely reflects the OA disease process predominantly affecting the lateral patellofemoral joint compartment (22). Therefore, if patellar malalignment is a feature of patellofemoral joint OA, then interventions with the potential to improve patellar malalignment, such as patellar taping, may be beneficial in the management of this disease.
Patellar taping was introduced by McConnell (23) and proposed to produce mechanical realignment of the patellar, thus improving its tracking within the trochlea and reducing knee pain. Studies that have evaluated the effect of patellar taping on patellar alignment in younger people with patellofemoral joint pain and healthy asymptomatic participants have produced inconsistent results. Whereas some studies noted significant improvements in patellar alignment with taping (24–27), others found no change (28, 29). The inconsistency of these results may be due to the measurement procedures used (i.e., different measures of alignment and weight-bearing or non–weight-bearing examinations), or the method of taping used, which was not fully disclosed by some authors. Importantly, the imaging modalities used (i.e., radiographs, computerized tomography, or magnetic resonance imaging [MRI]) have differed between studies. MRI provides greater information on the relationship of the patella to the femoral trochlea than radiographs, but few studies have utilized MRI scans to evaluate the effects of patellar tape (24, 26, 30). Further studies using well-described methodology with demonstrated reliability are required to add to the body of knowledge in this area. Although it is possible that patellar taping may be useful in the management of patellofemoral joint OA, the effect of this intervention on patellar alignment has not, to our knowledge, been evaluated in this patient group. OA is associated with many structural joint changes, including cartilage stiffening, osteophytes, joint effusion, and soft-tissue thickening (31, 32). Such changes could influence any potential effect of patellar tape. Therefore, it cannot be assumed that the taping effects observed in younger people will hold true for those with patellofemoral joint OA. The specific effect of patellar taping in patellofemoral joint OA needs to be investigated, because treatments with the potential to influence patellar malalignment may be important in the management of this condition.
Patellar taping has formed an integral component of the management of patellofemoral joint pain, with research demonstrating that taping can generally produce an immediate reduction in knee pain. A systematic review and meta-analysis recently conducted by our research group (33) determined that patellar tape decreased knee pain on a 100-mm scale by 16.1 mm (95% confidence interval [95% CI] −22.2, −10.0 mm) compared with no tape and by 10.9 mm (95% CI −18.4, −3.4 mm) compared with sham tape. Compared with no tape, medially-directed tape decreased pain by 14.7 mm (95% CI −22.8, −6.9 mm) and 20.1 mm (95% CI −26.0, −14.3 mm), respectively, for younger people with patellofemoral joint pain and those with mixed tibiofemoral and patellofemoral joint knee OA. Only 1 study included in the meta-analysis evaluated people with patellofemoral joint OA. Therefore, further research is required to confirm the usefulness of patellar tape as a pain-relieving technique in this subgroup of people with knee OA.
Our study aimed to compare patellar alignment of people with and without patellofemoral joint OA and to evaluate the immediate effects of patellar taping on patellar alignment and pain in people with patellofemoral joint OA.
SUBJECTS AND METHODS
Experiments were conducted using 14 people with patellofemoral joint OA and 14 healthy control participants. A cross-sectional study design was used to compare patellar alignment between people with and without patellofemoral joint OA. To evaluate the immediate effects of patellar taping on patellofemoral joint alignment and knee pain, a within-subjects design was employed.
Participants with patellofemoral joint OA and healthy volunteers age ≥40 years were recruited from the community. For the patellofemoral joint OA group, inclusion was based on 1) history of knee pain in the preceding week on ≥2 of the following activities: stair ambulation, squatting, rising from sitting, and locomotion (walking and/or jogging); 2) average overall knee pain >3 points on a 10-point numeric pain scale; 3) primary area of pain described in the anterior or retropatellar regions; 4) physical examination revealing tenderness in the peripatellar region; and 5) radiographic evidence of either an osteophyte of severity grade ≥2, or JSN of ≥1 with concurrent grade 1 osteophyte(s), in the patellofemoral joint on skyline radiograph. Individuals with concomitant tibiofemoral joint OA were included if the predominant source of symptoms was deemed to be from the patellofemoral joint. For the control group, participants were eligible if they had no current knee pain and reported no history of knee pain in the past year. Radiographs were not obtained from the control participants due to ethical and financial constraints.
Exclusion criteria for both the OA and control participants included 1) pain at a site distant to the patella; 2) concomitant injury or pathology in the lumbar spine, hip, or other knee joint structures; 3) history of fracture, arthroplasty, or osteotomy of the knee or hip; 4) inability to understand written and spoken English; 5) history of allergic reaction to tape; or 6) contraindications for MRI (e.g., implanted metal in vital organs).
In this study, the right knee was tested in the control group. In the OA group, the symptomatic knee, or most symptomatic knee in the case of bilateral symptoms, was tested (the right knee in 8 people and the left knee in 6 people). The study was approved by the University of Melbourne Human Research Ethics Committee. All participants provided written informed consent.
Participant characteristics, including age, height, and weight, were recorded. The Western Ontario and McMaster Universities Osteoarthritis Index (34) was used to assess pain (score range 0–20, with higher scores indicating worse pain), stiffness (score range 0–8, with higher scores indicating greater stiffness), and physical function (score range 0–68, with higher scores indicating worse function) in the OA group. In participants with OA, the radiographic severity of tibiofemoral OA was assessed with the Kellgren/Lawrence scoring system (35). Patellofemoral joint osteophytes and JSN were scored in each of the medial and lateral compartments using the Osteoarthritis Research Society International Atlas for Radioanatomic Positioning of the Knee (36) on a 0–3 scale, where 0 = normal, 1 = mild, 2 = moderate, and 3 = severe.
All MRIs were performed on a 1.5T General Electric HDx MRI scanner (GE Medical Systems, Milwaukee, WI) using a 4-channel MedRad transmit–receive phased-array knee coil. All participants were positioned in a supine, feet-first orientation. Comfort sponges were removed from beneath the buttocks and ankles to facilitate an increased range of knee flexion within a commercially-available clinical imaging coil. A rectangular positioning sponge was placed beneath the posterior knee crease to ensure a consistent angle of knee flexion (15°) and to maintain uniformity of positioning between participants.
The imaging protocol consisted of a single data set of 3-dimensional T1-weighted fat-suppressed gradient echo images (repetition time 43 msec, time to echo 5 msec) with a slice thickness of 1 mm, a 0-mm interslice gap, 1 excitation, a field of view of 200 × 200 mm, and a matrix of 256 × 256 pixels. Spatial resolution was thus 0.78 × 0.78 × 1 mm. Acquisition time was ∼10 minutes, depending upon the number of slices required to capture the relevant anatomy. The MRI data were stored in Digital Imaging and Communication in Medicine (DICOM) format and deidentified with regard to participant name, group (OA or control), and condition (tape or no tape).
Patellar alignment measurement.
Patellar alignment was assessed from deidentified transverse (axial) MRI scans using DICOM viewer software, version 1.3.5 (DicomWorks, Puech and Boussel, Lyon, France) by 1 examiner (GPM) who remained blind to the patient identification, group condition (OA or control), and tape condition (tape or no tape). Measurements of patellar position included lateral displacement, bisect offset, and lateral patellar tilt angle. For all measurements, the median of the images displaying the patella was used for analysis. The methods used to calculate the measurements of patellar alignment are outlined in Figure 1. The lateral displacement measurement was obtained using the method described by Powers et al (37). The measurements of bisect offset and patellar lateral tilt angle were measured according to the procedures described by Kalichman et al (16, 17).
Prior to data analysis, the intrarater reliability of the alignment measurements was determined. Patellar alignment was measured from the MRI scans of all the participants (n = 28) by the same investigator (GPM) on 2 occasions, 1 week apart. To ensure consistency, measurements were performed in batches of 10 scans, and before each batch the investigator reassessed 5 of the previously measured scans.
For the taping study, pain experienced while performing a single-leg squat 5 times was recorded on a 100-mm visual analog scale (VAS). Pain data were measured from the VAS by an examiner (KMC) who was blind to the tape condition.
MRI images were obtained from patellofemoral joint OA participants with and without the application of patellar tape. The testing order (tape, no tape) was randomly allocated. Taping to correct patellar alignment was applied in a standardized manner by the same investigator, who is an experienced physiotherapist (RSH). Where necessary, skin was shaved prior to tape application. Two pieces of rigid tape (Leuko Sportstape Premium Plus; Beiersdorf Australia, Sydney, New South Wales, Australia) were used to apply a medial patellar glide, as well as a medial and superior tilt to the patellar. To unload the infrapatellar fat pad, another 2 pieces of tape were applied distal to the patella. This taping procedure has previously been shown to be effective in reducing pain in knee OA (38). Hypoallergenic tape (Fixomull stretch, Beiersdorf Australia) was applied beneath the rigid tape to prevent skin irritation. Participants were asked to report any symptoms of skin irritation while they wore the tape, and the knee was inspected after the tape was removed.
Analyses were performed using the Statistical Package for the Social Sciences, version 13 (Norusis/SPSS, Chicago, IL) with an alpha level of 0.05. Descriptive information was examined via mean ± SDs and frequencies, where appropriate. Intrarater reliability was assessed using an intraclass correlation coefficient (ICC) (3,k) and the standard error of measurement (SEM). Independent t-tests were used to compare means between the participant groups. An analysis of covariance was also performed to evaluate whether sex influenced the outcomes of the between-group comparisons. Paired 2-tailed t-tests were used to compare variables between taping conditions.
Characteristics of the study group.
Characteristics of the participants with patellofemoral joint OA (n = 14) and the controls (n = 14) are described in Table 1. The groups were similar regarding age, height, weight, body mass index, and sex (P > 0.05). The severity of JSN and osteophytes in the medial and lateral patellofemoral joint compartments is described in Table 2.
Table 2. Severity of medial and lateral compartment patellofemoral joint disease of participants with OA (n = 14)*
Values are the number (percentage). Disease severity based on the Osteoarthritis Research Society International Atlas for Radioanatomic Positioning of the Knee (36), using a 0–3 scale where 0 = normal, 1 = mild, 2 = moderate, and 3 = severe). OA = osteoarthritis; JSN = joint space narrowing.
Comparison of patellar alignment between groups.
The intrarater reliability of the measurements was high for lateral displacement (ICC 0.988, SEM 0.97%), bisect offset (ICC 0.988, SEM 1.55%), and patellar lateral tilt angle (ICC 0.966, SEM 1.28°). People with patellofemoral joint OA had more laterally positioned patellae compared with their pain-free counterparts (Table 3). The lateral displacement measurement indicated that a mean of 17% of the patella was positioned lateral to the femoral trochlea in the patellofemoral joint OA group, compared with a mean of 5% of the patella in the control group. The bisect offset measurement revealed that a mean of 71% of the patella was positioned lateral to the deepest point of the femoral trochlea in the patellofemoral joint OA group, compared with a mean of ∼50% of the patella in the control group. The patellar lateral tilt angle was similar in both groups. The inclusion of sex as a covariate to the between-group comparisons did not affect the results.
Table 3. Comparison of group means for patellar alignment between patients with patellofemoral joint OA and asymptomatic participants*
Patellar alignment measures
Patellofemoral joint OA (n = 14)
Controls (n = 14)
Between-group difference, mean (95% CI)
Values are the mean ± SD unless otherwise indicated. OA = osteoarthritis; 95% CI = 95% confidence interval.
Lateral displacement, %
17.04 ± 7.96
5.08 ± 4.71
11.96 (6.83, 17.10)
Bisect offset, %
71.55 ± 13.08
51.69 ± 5.03
19.86 (11.94, 27.77)
Lateral patellar tilt angle, degrees
16.06 ± 9.47
17.36 ± 2.60
−1.31 (−6.90, 4.29)
Effects of patellar tape on patellar alignment and pain.
The mean ± SDs of the patellar alignment measures for the patellofemoral joint OA participants with tape and no tape are presented in Figure 2. Patellar tape resulted in a significant reduction in lateral displacement (mean difference 2.94%; 95% CI 0.37, 5.51%; P = 0.028) and increase in patellar lateral tilt angle (mean difference 3.57°; 95% CI 2.14, 4.91°; P < 0.001). These results indicate a lessening of lateral patellar malalignment. There was no change in the bisect offset with tape (mean difference 0.58%; 95% CI −3.35, 4.50%; P = 0.757). Mean pain during squatting decreased with tape by 15.3 mm (95% CI 0.40, 30.3 mm; P = 0.045) compared with the no-tape condition.
Patellofemoral joint OA is increasingly being recognized as a distinct subgroup of knee OA (5, 12, 39, 40) as a consequence of its prevalence and its considerable impact on the pain and physical dysfunction experienced by people with knee OA. Due to the lack of available treatments for patellofemoral joint OA, it is imperative to develop and evaluate interventions specifically for people with OA that affect the patellofemoral joint compartment. This study found that the patella was more laterally positioned in people with patellofemoral joint OA compared with asymptomatic controls. In the patellofemoral joint OA group, standardized patellar taping resulted in an immediate reduction in lateral patellar displacement and tilt, and an immediate reduction in pain.
This study compared patellar alignment between people with and without patellofemoral joint OA. Lateral patellar displacement was, on average, 12% greater in those with patellofemoral joint OA, and bisect offset was nearly 20% greater. These mean differences were ∼6 times larger than the measurement error observed, and are therefore likely to be clinically relevant. Although the finding of patellar malalignment in people with patellofemoral joint OA observed in the current study requires further confirmation, this result may represent a link between the subgroup of people with patellofemoral joint pain and malalignment and the development of patellofemoral joint OA. Despite the inability to measure joint stress in vivo, it has long been considered that lateral malalignment increases joint stress in the lateral patellofemoral joint compartment (13, 14, 41). Furthermore, cohort studies of people with knee OA have shown that a more laterally aligned patella has adverse consequences, because it is associated with greater functional impairment (21), more severe OA (more JSN and less cartilage thickness) (16–18), and greater structural deterioration in the patellofemoral joint (19). Treatments such as patellar taping that address patellar malalignment may be able to alleviate some of the physical dysfunction associated with patellofemoral joint OA and may have the potential to slow disease progression.
This is the first study to our knowledge to investigate the effects of patellar tape on patellar alignment in people with patellofemoral joint OA. The observed differences were modest, with lateral displacement reduced by ∼3% and patellar lateral tilt angle decreased by ∼4%. However, these mean differences were more than double the magnitude of the recorded measurement error. The observation that patellar tape can influence patellar malalignment may have important consequences for people with patellofemoral joint OA. Until larger longitudinal studies establish the long-term effects of patellar tape on lateral patellar alignment, the ability of such an intervention to influence the symptoms and progression of patellofemoral joint OA will remain speculative. Nevertheless, the findings of this study are encouraging, and indicate that patellar tape may be beneficial for people with patellofemoral joint OA.
This study provides further evidence to support the use of patellar tape in people with patellofemoral joint OA. The mean pain reduction observed (15.3 mm) was similar to the weighted mean difference observed for the use of patellar tape in younger people with patellofemoral joint symptoms and for people with mixed tibiofemoral joint and patellofemoral joint knee OA (33). It is possible that the changes in patellar alignment noted in this study may have been associated with the observed changes in pain. However, differences in the measurement of each variable (alignment was measured in a static, non–weight-bearing posture, whereas pain was measured during a dynamic squatting activity) preclude any evaluation of such a relationship.
One potential mechanism that might account for the observed pain relief is a change in the patellofemoral joint contact area, similar to that obtained using a patellar brace by Powers and colleagues (37, 42). This change in patellofemoral joint contact area was associated with reduced patellofemoral joint stress, and it is feasible that patellar tape may produce a similar effect. Additionally, it is possible that alternative mechanisms may explain the pain-relieving effects of patellar tape. Importantly, the patellar tape used in this study also included a component designed to reduce the load on the infrapatellar fat pad. Because the infrapatellar fat pad is one of the most pain-sensitive structures in the knee (43–46) and is often described as a potential source of pain in knee OA (43–45, 47), it is possible that the patellar tape may have reduced knee pain through its influence on the peripatellar soft tissue structures. Furthermore, the potential for nonphysical mechanisms to influence the response to tape must be acknowledged. Our meta-analysis observed that approximately half of the of the pain reduction observed with patellar tape could be attributed to placebo and/or other effects (33). Regardless of the mechanism underpinning the pain-relieving effects, patellar tape has potential as a temporary pain-relieving intervention in this patient population.
The current study did have limitations. In an attempt to evaluate alignment and the effects of taping at a clinically relevant knee angle, we performed our MRI images at 15° knee flexion, the maximum flexion possible within the knee coil. The images were performed in non–weight-bearing posture, which means that the lateral patellar alignment may have been underestimated, limiting the validity of the measures. However, an identical methodology was used for all participants in an attempt to reduce any effect of weight-bearing posture on the comparisons of patellar alignment. Future studies in larger populations are needed to verify these results, and these studies should be performed for a range of knee flexion angles (including full knee extension) and in weight-bearing posture or with quadriceps contraction, in order to more closely approximate functional activities. Furthermore, it was not possible to constrain the knee flexion angle during the pain- provoking activity (squatting). Because the knee flexion angle will influence a pain response, future studies should control for this variable.
Another limitation of this study is that it only evaluated the immediate effect of tape on patellar alignment and pain. Patellar tape will loosen with activity, and it is possible that the immediate effects observed in this study would lessen over time. Further studies are needed to determine how frequently patellar tape needs to be reapplied in order to maintain its beneficial effects.
Future studies could also evaluate the effects of patellar bracing in people with patellofemoral joint OA. Patellar bracing is another treatment designed to influence patellar alignment (48) and is frequently considered as an alternative to patellar tape. Patellar bracing has been evaluated in younger people with patellofemoral joint pain and has been shown to reduce symptoms (37, 42, 49) and patellar malalignment (37, 50). Although this treatment has not been evaluated in people with patellofemoral joint OA, patellar bracing may have similar effects on patellar alignment to those of patellar taping. Importantly, patellar bracing can and should be considered for patients who cannot tolerate patellar tape.
In conclusion, people with patellofemoral joint OA exhibited greater lateral patellar malalignment compared with their asymptomatic counterparts, and patellar tape reduced this malalignment. Patellar tape also resulted in immediate pain reduction. Patellar taping is an inexpensive treatment that is easily applied by an experienced physiotherapist and is associated with minimal side effects (51). There are notably few interventions that have been demonstrated to reduce patellar malalignment and pain in patellofemoral joint OA. Considering the potential for patellar malalignment to contribute to the severity and progression of disease and symptoms, and considering the consequences of chronic pain on quality of life, patellar tape could potentially be an effective treatment for those with patellofemoral joint OA.
All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be submitted for publication. Dr. Crossley had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study conception and design. Crossley, Hinman.
Acquisition of data. Crossley, Marino, Macilquham, Hinman.
Analysis and interpretation of data. Crossley, Marino, Schache, Hinman.