The influence of patellar bracing on patellar and knee load-distribution and kinematics: an experimental cadaver study

Patellar tendinopathy: an overview of prevalence, risk factors, screening, diagnosis, treatment and prevention

Patellar tendinopathy (PT), or jumper's knee, is an overuse injury that occurs in professional, as well as recreational, athletes. This condition is a noncontact injury, typically characterized by gradually increasing pain in the patellar tendon. It is prevalent in participants of several sports, but it occurs mostly in jumping sports. The diagnosis of PT is primarily clinical; however, imaging techniques can be useful as well. Risk factors differ between sexes, playing conditions, the kind of sport, playing level and personal characteristics. Screening is an essential tool to assess PT. This condition affects athletic performance and often persists for years. The use of preventative methods is imperative because of the persistence of this condition, especially in elite athletes who sometimes end their career after long and failed treatments. There are a wide variety of treatment and rehabilitation options available, the majority of which are non-operative, such as eccentric exercises, cryotherapy, platelet-rich plasma (PRP) injections, and anti-inflammatory strategies. If conservative treatment fails, surgery is the next most preferable step. Even though there are many surgical treatment methods, there is no clear evidence on what is the most effective approach to address PT. Taking this into consideration, as well as the extent of this clinical entity, novel therapeutic techniques, as well as screening and prevention methods, are expected to emerge in the near future.

Effect of flexion-resist and extension-assist knee orthosis on electromyographic activities of quadriceps during lateral stepping

Knee orthoses can potentially reduce muscular activities of the quadriceps. The aim of this study was to investigate the effect of a custom flexion-resist and extension-assist knee orthosis on electromyographic activities of quadriceps during lateral stepping (step-up and step-down). Flexion resistance and extension assistance mechanisms were set by a pair of linear springs built into the orthotic knee joints. Electromyography (EMG) signals were collected from rectus femoris (RF), vastus medialis obliquus (VMO), and vastus lateralis (VL) during lateral step-up and lateral step-down activities in 7 healthy young adults. Peak normalized root mean square (RMS) EMG signals of each muscle, as well as VMO:VL ratio, were compared between orthotic and nonorthotic conditions using the Wilcoxon signed-rank test. The knee orthosis significantly reduced the normalized RMS EMG signals of the RF and VL during lateral stepping ( p < 0.05). No significant difference was found in the VMO. The VMO:VL ratio significantly ( p < 0.05) increased under orthotic condition. The experiments demonstrated that the knee orthosis reduces the peak normalized RMS EMG signals of RF and VL, and alter the VMO:VL ratio of quadriceps in healthy young adults. Therefore, this study suggests that the flexion-resist and extension-assist knee orthosis may be effective in reducing muscular activities of RF and VL, which may alleviate patellofemoral loading. Future studies should delve into the effects of the knee orthosis in individuals with patellofemoral pain.

Bracing for the Patellofemoral Joint

Patellofemoral disorders are common causes of knee pain that result in frequent visitations to musculoskeletal care clinics. Patellar tendinopathy, patellar instability and patellar maltracking, and pain are some of the most common pathologies resulting in patellofemoral dysfunction. For each of these diagnoses, there are unique orthoses and braces available, some of which are uniquely designed to address the pathology involved. While the spectrum of patellofemoral disorders is wide ranging and can often be challenging to treat, bracing frequently plays a large role in the overall treatment algorithm. In this article, we summarized the current literature and treatment recommendations related to the most common types of patellar braces. We performed a thorough review of randomized controlled trials and up to date literature to reach well-informed conclusions on current best practice regarding the uses of patellar braces for patellofemoral disorders.

Patellofemoral Joint Contact Pressures: Current Concepts and Use in Patellar Instability Studies

The patellofemoral joint is thought to be a common source for knee pain. Improper alignment and function of the patellofemoral joint can lead to abnormal contact pressures, which may explain patients' symptoms. In this review, the authors examine techniques for measuring patellofemoral joint contact pressures and summarize the relevant patellofemoral joint anatomy and contact pressures in normal knee kinematics. Finally, they discuss the results of studies investigating contact pressure changes in cases of patellar instability. This includes both reconstruction of the medial patellofemoral ligament and tibial tubercle osteotomy. [Orthopedics. 2019; 42(2):e172-e179.].

Immediate effect of infrapatellar strap on pain and jump height in patellar tendinopathy among young athletes

BACKGROUND:

Infrapatellar strapping is a treatment technique used in various knee pathologies; however, its effect on pain and functional performance among young athletes has not been studied.

OBJECTIVES:

To evaluate the effect of infrapatellar strap on pain and jumping performance among young athletes diagnosed with patellar tendinopathy.

STUDY DESIGN:

Pre-/post-test (within-subject research design).

METHODS:

A total of 16 young male basketball and volleyball athletes (age range, 12-18 years) diagnosed with patellar tendinopathy were included in the study. Infrapatellar strap was applied beneath the patella, over the patellar tendon. The athletes performed four jumping tests: squat jump, drop jump, single-leg jump, and jumps 30 s test, with and without the strap. Pain severity in the symptomatic knee during jumping was assessed using a visual analog scale and jumping performance parameters were assessed using an Optojump Next optical measurement system.

RESULTS:

Pain severity reported by the participants decreased in drop test, single-leg jump test, and jumps 30 s test while using the infrapatellar strap compared with no strap condition ( p < 0.05). No significant difference in jumping performance was found between jumping with and without the strap.

CONCLUSION:

The infrapatellar strap was effective in reducing local pain among young male athletes without altered jumping performance.

CLINICAL RELEVANCE

The infrapatellar strap can be recommended to use during physical activity as part of the physical therapy treatments for patellar tendinopathy. Given the low cost, ease to use, and being a non-invasive method without adverse effects, it is an appropriate intervention for young athletes.

Single-limb landing biomechanics are altered and patellar tendinopathy related pain is reduced with acute infrapatellar strap application

BACKGROUND

Patellar tendinopathy, a common condition of the knee, is often treated with patellar tendon straps to control pain during dynamic activity. Little is known regarding their effect on pain, landing kinematics and kinetics with their application. The purpose of this study was to determine if patellar tendon straps influenced pain, kinematics at landing and ground reaction forces in individuals with patellar tendinopathy versus healthy controls.

METHODS

Thirty participants with patellar tendinopathy and 30 controls participated. They completed single-limb landings with and without patellar tendon straps while pain, three-dimensional kinematics and vertical ground reaction forces were measured. A multivariate analysis of variance was completed to determine the differences in strapping condition and group for the dependent variables.

RESULTS

Individuals with patellar tendinopathy demonstrated a significant decrease in pain (no strap=37.1±22.1mm (mean±SD), strap=28.0±18.5mm (mean±SD)). With the strap at landing all participants displayed less hip rotation (F=7.16, p=.01), knee adduction (F=10.20, p=.002), ankle inversion (F=4.60, p=.04), and peak vertical ground reaction force (F=7.30, p=.009).

CONCLUSIONS

Patellar tendon straps reduced pain in those with patellar tendinopathy. Additionally, with the strap, individuals landed in a more neutral alignment and decreased landing forces which could provide a benefit to those with patellar tendinopathy.

Patellar tendon straps decrease pre-landing quadriceps activation in males with patellar tendinopathy

OBJECTIVE

To determine if patellar tendon straps altered quadriceps' muscle activity during a drop-jump landing in males with and without patellar tendinopathy.

DESIGN

Case-control.

SETTINGS

Biomechanics Research Laboratory.

PARTICIPANTS

Twenty recreationally-active males participated: ten (age = 21.3 ± 2.4 years, height = 182.8 ± 5.3 cm, mass = 81.7 ± 8.6 kg) with patellar tendinopathy; ten (age = 22.0 ± 1.6 years, height = 185.7 ± 4.5 cm, mass = 82.2 ± 9.8 kg) were healthy with no history of tendinopathy.

MAIN OUTCOME MEASURES

Electromyography (EMG) data for the vastus medialis (VM), rectus femoris (RF), and vastus lateralis (VL) muscles were collected. Five 2-legged 40 cm drop-jumps were performed wearing a patellar tendon strap and 5 with no-strap in a counterbalanced order. Root-mean square EMG (REMG) values of the VM, RF, and VL were averaged for a pre-landing and post-landing interval. Multiple mixed-model two-way ANOVAs were performed to determine the effect of tendinopathy and strapping condition on REMG values for each muscle.

RESULTS

For the pre-landing interval, all participants displayed lesser VL EMG activation (0.44 ± 0.19%, 0.53 ± 0.27%, respectively; p = 0.007, d = 0.39) in the no-strap compared with the strap condition.

CONCLUSIONS

When wearing a strap, all participants demonstrated lower VL activation prior to landing which may be helpful in reducing tensile stress at the tendon. These effects may be clinically important in modulating pain in those with patellar tendinopathy.

The immediate effect of patellar tendon strap on weight-bearing asymmetry during squatting in patients with unilateral knee osteoarthritis: A pilot study

BACKGROUND

Knee osteoarthritis has commonly been associated with a symptom of pain resulting in an inter-limb weight-bearing asymmetry during functional tasks. Patellar tendon strap is one of the non-pharmacologic interventions to alleviate knee pain.

OBJECTIVES

To investigate the immediate effect of a patellar tendon strap on weight-bearing asymmetry during squatting in people with unilateral knee osteoarthritis.

STUDY DESIGN

Cross-sectional study.

METHODS

Ten patients with unilateral knee osteoarthritis and 10 healthy subjects were included in the study. Weight-bearing asymmetry of patients was assessed using a weight-bearing squat test during squatting at 30° and 60° both with and without patellar tendon strap. Pain intensity was assessed during squatting in unstrapped and strapped conditions with Visual Analog Scale.

RESULTS

The decrease in weight-bearing asymmetry values immediately after wearing patellar tendon strap during 30° (p = 0.006) and 60° (p = 0.011) of squatting tests was significantly higher in knee osteoarthritis patients than in healthy subjects. Reported pain intensity was similar in unstrapped and strapped conditions (p = 0.066).

CONCLUSION

The results of this study showed improved inter-limb weight-bearing symmetry during squatting. Further research with larger sample sizes investigating the effect of patellar tendon strap on weight-bearing asymmetry during functional activities in people with knee osteoarthritis is warranted.

CLINICAL RELEVANCE

Patellar tendon straps (easily fit and cheap unlike knee braces) had more improvements in inter-limb weight-bearing symmetry during squatting in people with knee osteoarthritis compared to healthy subjects. This study is a new insight for future studies to investigate clinical benefits of wearing patellar tendon straps in this population.

Patellar Tendinopathy

Context:

Patellar tendinopathy is a common condition. There are a wide variety of treatment options available, the majority of which are nonoperative. No consensus exists on the optimal method of treatment.

Evidence Acquisition:

PubMed spanning 1962-2014.

Study Design:

Clinical review.

Level of Evidence:

Level 4.

Results:

The majority of cases resolve with nonoperative therapy: rest, physical therapy with eccentric exercises, cryotherapy, anti-inflammatories, corticosteroid injections, extracorporeal shockwave therapy, glyceryl trinitrate, platelet-rich plasma injections, and ultrasound-guided sclerosis. Refractory cases may require either open or arthroscopic debridement of the patellar tendon. Corticosteroid injections provide short-term pain relief but increase risk of tendon rupture. Anti-inflammatories and injectable agents have shown mixed results. Surgical treatment is effective in many refractory cases unresponsive to nonoperative modalities.

Conclusion:

Physical therapy with an eccentric exercise program is the mainstay of treatment for patellar tendinopathy. Platelet-rich plasma has demonstrated mixed results; evidence-based recommendations on its efficacy cannot be made. In the event that nonoperative treatment fails, surgical intervention has produced good to excellent outcomes in the majority of patients.

Influence of infrapatellar and suprapatellar straps on quadriceps muscle activity and onset timing during the body-weight squat

The use of knee braces for the treatment of patellofemoral pain syndrome (PFPS) is widely documented, yet the mechanism by which such braces alleviate knee pain remains unclear. This study attempted to clarify this issue by simplifying the brace to the level of only straps. The effectiveness of an infrapatellar strap for PFPS remains controversial, and the use of a suprapatellar strap has not yet been studied. Quadriceps muscle activity and onset timing parameters were measured with surface electromyography (EMG) during a body-weight squat in 19 healthy subjects during 4 different knee-strapping conditions (infra, supra, both, and none). No differences in normalized mean or peak EMG activity in any part of the quadriceps were found. The onset timing of the vastus lateralis (VL) was significantly delayed when using an infrapatellar strap (p < 0.05) or both straps (p < 0.05) and marginally delayed when using a suprapatellar strap (p < 0.10) in comparison with the no-strap (control) condition. No differences in the vastus medialis oblique (VMO) onset timing or VMO-VL onset timing difference were found among the strapping conditions, although an improvement in timing was noted with the suprapatellar condition. The results provide novel evidence that the application of an infrapatellar strap, suprapatellar strap, or both straps improves quadriceps muscle timing imbalances by delaying VL onset. Because the largest delay in VL onset occurred when wearing both straps, the combined application of an infrapatellar and suprapatellar strap may be the most beneficial in managing patellofemoral pain. Knee straps, unlike braces, are cost effective, nonrestrictive, and can be universally fitted to any knee and based on the results deserve further study in the patellofemoral pain population.

Infrapatellar Straps Decrease Patellar Tendon Strain at the Site of the Jumper's Knee Lesion: A Computational Analysis Based on Radiographic Measurements

BACKGROUND

The impetus for the use of patellar straps in the treatment of patellar tendinopathy has largely been based on empirical evidence and not on any mechanistic rationale. A computational model suggests that patellar tendinopathy may be a result of high localized tendon strains that occur at smaller patella-patellar tendon angles (PPTAs).

HYPOTHESIS

Infrapatellar straps will decrease the mean localized computational strain in the area of the patellar tendon commonly involved in jumper's knee by increasing the PPTA.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty adult males had lateral weightbearing and nonweightbearing radiographs of their knees taken with and without 1 of 2 infrapatellar straps at 60° of knee flexion. Morphologic measurements of PPTA and patellar tendon length with and without the straps were used as input data into a previously described computational model to calculate average and maximum strain at the common location of the jumper's knee lesion during a simulated jump landing.

RESULTS

The infrapatellar bands decreased the predicted localized strain (average and maximum) in the majority of participants by increasing PPTA and/or decreasing patellar tendon length. When both PPTA and patellar tendon length were altered by the straps, there was a strong and significant correlation with the change in predicted average localized strain with both straps.

CONCLUSION

Infrapatellar straps may limit excessive patella tendon strain at the site of the jumper's knee lesion by increasing PPTA and decreasing patellar tendon length rather than by correcting some inherent anatomic or functional abnormality in the extensor apparatus.

CLINICAL RELEVANCE

The use of infrapatellar straps may help prevent excessive localized tendon strains at the site of the jumper's knee lesion during a jump landing.

Foot biomechanics and initial effects of infrapatellar strap on gait parameters in patients with unilateral patellofemoral pain syndrome

BACKGROUND

There is limited information on the relationship between plantar foot pressure and patellofemoral pain syndrome (PFPS). In addition, there is not enough research on the effects of an infrapatellar strap on PFPS.

OBJECTIVE

The aim of this study was to evaluate the immediate effects of an infrapatellar strap on dynamic pedabarography in patients with unilateral PFPS.

METHODS

Clinical case control study design. 18 females subjects with unilateral PFPS were included in the study. Gait parameters were tested using pedabarography during barefoot walking with and without an infrapatellar strap.

RESULTS

There were no statistically significant differences in gait trials comparing infrapatellar strap to no strap (P>0.05). In addition, a significant difference (P=0.043) in the % forefoot surface on the involved side demonstrated that body weight is transferred to medial aspect of the foot.

DISCUSSION

Although our results show a difference between the forefoot surface % of the affected and unaffected sides of subjects with PFPS there was no indication that an infrapatellar strap had any immediate effect on this parameter.

CONCLUSION

It is not clear whether PFPS is a cause or effect of abnormal gait. Further research is warranted to investigate the long-term effects of wearing an infrapatellar strap and associated altered foot biomechanics due to PFPS.

A randomized trial of patellofemoral bracing for treatment of patellofemoral osteoarthritis

PURPOSE

The number of effective knee osteoarthritis (OA) interventions, especially those tailored to specific compartmental involvement, are small. The objective of this study was to determine the efficacy of a realigning patellofemoral (PF) brace in improving pain and function among persons with symptomatic lateral PF OA.

METHOD

We conducted a double blind, randomized crossover trial of a realigning PF brace for persons with lateral PF OA. Participants had lateral PF OA with anterior knee symptoms on most days of the month, lateral PF joint space narrowing, and radiographic evidence of a definite osteophyte in the PF joint. We compared two treatments: (1) Control treatment consisting of a BioSkin Q Brace with patellar realigning strap removed; and (2) Active treatment consisting of a realigning BioSkin Q Brace with the strap applied. For each participant, the trial lasted 18 weeks, including 6 weeks each of active and control treatment period separated by a 6-week washout period. The order of treatments was randomized. The primary outcome was change in knee pain on the visual analog scale (VAS). Secondary outcomes included WOMAC pain, function, and stiffness. An unstructured correlation matrix for observations within participants was used in generalized estimating equation fitting to derive a linear regression model that expressed the relation between the intervention and change in VAS pain.

RESULTS

80 participants (63 F) with a mean age and body mass index of 61 years and 28 kg/m(2), respectively, were randomized by order of treatment. A model examining the main effects for change in VAS knee pain (0-100) demonstrated no significant treatment effect (-0.68 VAS units, 95% CI: -6.2, 4.8 units, P=0.81) and no differential carryover effect. There was also no significant difference between active and control treatments for WOMAC pain, function, or stiffness outcomes.

CONCLUSION

The effects of a specific realigning PF brace are not of clinical or statistical significance.