This day conference was at the tail end of a research retreat with leading Patellofemoral pain researchers in beautiful Vancouver City. I’m going to do my best to share the highlights of the conference and to share some of the in-formal conversations I had. It is important to realize that these notes are my interpretations of content and may not reflect the intended meaning.
I’m going to release the information in chunks daily. So I can review the notes and so I can add comments where appropriate.
Jenny McConnell
All roads lead to Rome – increased lateral patellar tracking causes PFP and there are many potential causes of increased lateral patellar tracking (proximal and distal factors)
Prischa Jeptoo – London 2012 Silver Medalist
What would you do?? Would you change and alter her mechanics?? If you changed her mechanics would she run faster?? She experience no pain and she runs fast – how is this possible considering her mechanics??
- We need to understand the complex interaction between the effects of Pain and Fear of Pain (extrinsic factors) – muscle, cortical level, muscle timing and coordination, behavior
- Different people need different things – NO one patellar femoral patient we need to always understand the unique contributors.
- In patellofemoral pain where is the pain coming from?? Dye has investigated the pain sensitive structures in the knee. Retropatellar cartilage is not pain sensitive, but the underlying subchondral bone is pains sensitive. More sensitive to both is the fat pad. (I would consider Jenny to be a leading clinician on fat pad as a pain generator…is this something we overlook – see my conversation with said clinician)
- If the fat pad is aggravated you can’t extend the leg – this is an important consideration and it is helpful differentiator (I will talk more about the implications of the FAT PAD)
- We need to find interventions that are simple – allow the patient to do them anytime and anyplace
Eric Witvroux Overview of Consensus
Local Factors:
- Diagram for Malalignment -> PFP
- Where is the malalignment coming from
- People with lower levels of quad are at increased risk of PFP (but PFP is multifactorial to threshold)
- Flexibility
- Knee Proprioception – awareness
- Patellar mobility (usually hypomobility)
- Neuromuscular coordination
- Timing VMO / VL
- Amount of VMO / VL activity
- Eccentric Qcep defiencies – more difficult to control than concentrically (cortically) first also to be effected (This is an important highlight and it will be something that I blog about in the future…we see this all the time with our athletes. When injured their landing and force absorption becomes compromised. Likewise the ground contract interaction, whereby an athlete utilizes momentum and develops elastic energy is extremely complex and it is an athletic differentiator for elite vs. average athletes)
- Tissue homeostasis – overuse model – load and frequency
- Zone of subphysiological load
- Zone of homeostasis
- Zone of supraphysiological overload
- Zone of structural failure
- Complex Pain Mechanisms
- ID subgroups of PFPS
- Better understand the neuromuscular factors
Chris Powers (PROX)
- Dynamic MRI – closed chain vs. closed chain. Tracking is very different…femur moves in closed chain on a stable patella (track and train model – track moves in closed chain)
- Knee Valgus is based on hip internal rotation and hip adduction
- Static Q-angle doesn’t mean anything – it does not predict what happens in movement
- Reviewed Consensus Statements
- Over 15 published papers of PFP linked with hip weakness but not necessary predictive prospectively (cause and effect???? Are we evaluating hip function appropriately – it functions isometrically to immediatley control the pelvis and knee)
- Spoke about the importance of HIP EXTENSOR ENDURANCE (possible role of the hamstring in PFP….we must think of all the muscles working in concert for appropriate movement – what is the value of motor co-ordination (timing) based on EMG with anatomical variants and task specificity.
- Forward trunk inclination can decrease loading at the knee, backward trunk inclination can increase loading at the knee (this trunk position is very valuable for patients who are having troubles going up and down stairs – load through hips, decrease load through the knee by increasing forward trunk inclination in both)
- Need to have large prospective studies!
- Male vs. Female sex difference (we need to study this…)
Natalie Collins (DISTAL)
- Midfoot Mobility – relaxed vs. stance (McPoil) See Article
- Michael Callaghan – Man U
- 11 RCT on therapeuctic interventions since 2009
- Research with SUBGROUPS for RCT
- Case-control studies have also reported greater midfoot mobility in patients with PFP, measured when moving from non–weight bearing to static relaxed stance (midfoot height),19 and as navicular drop.3, 4.
- There is emerging evidence of a relationship between rearfoot eversion and tibia and hip motion in PFP. Peak rear foot eversion has been shown to be positively correlated with peak tibia internal rotation in PFP (but not controls), while greater rearfoot eversion range of motion was also positively correlated with hip adduction range in
both PFP and controls. This has implications for patellofemoral joint loading because both tibia internal rotationand hip adduction are likely to increase dynamic knee valgus
(medial knee collapse) and patellofemoral joint stress.
- Static measures of foot posture appear to be an inadequate representation of dynamic foot function. Static alignment measures have not been identified as risk factors for PFP development.25,27 However, measures of foot mobility can distinguish between PFP and controls
- Based on recent findings of reduced dorsiflexion in runners with a history of PFP, it has been proposed that increased rearfoot eversion during running may be a mechanism to unlock the midfoot and allow a compensatory increase in midfoot dorsiflexion. The resulting reduced ability to resupinate the foot during late stance to form a rigid lever may prolong dynamic knee valgus.
- While research has continued to focus on foot pronation, other variations in foot posture may be associated with PFP, particularly in different at-risk populations. A
prospective study reported that a more lateral rollover pattern of plantar pressure was a risk factor for PFP development in predominantly male military recruits which may suggest a predominant gait pattern in these individuals.
Discussion
No intervention that has been able to show a change in patellar tracking
Irene Davis
- Mismatch – are we designed to run / or are we doing something wrong like a wing being injured in a bird
- 79% of runners will sustain an injury in a given year (YES 79%)
- We have well-designed feet that allow us to run (Rigid Lever, mobile adapter, spring) 26 bones, 33 joints with 6 degrees of freedom of movement with 4 layers of arch muscles
- She gave a nice overview of the history of running shoes – sagebrush bark sandals to the modern running shoe
- Jones (2010) – Injury reduction effectiveness of selecting running shoes based on plantar shape
- “This prospective study demonstrated that assigning shoes based on the shape of the plantar foot surface had little influence on injuries even after considering other injury risk factors”
- Lateral ground reaction forces also present with RFS – significant
- Benefits of Barefoot Running
- Gentler Landing (McNitt-Gray, 2006, Bishop et al, 2006, Ferris et al 1999)
- Shorter Stride (Heiderscheidt et al 2010, Bonacci et al 2010)
- Greater Sensory Input
- Increased Foot Strength
- Transitional shoes are more similar to traditional shoes than BF
- Transitional Shoes Greater impact than traditional shoes (Willy & Davis 2013)
- Larger level arm
- Rate of Loading not Peak Load that determines PFP and Tibial Stress Fractures
- Prospective Study that has been able to show that those who demonstrated low peak and rate don’t become injured (in review – this is very fascinating)
- We have an amazing ability to modulate GRF need to learn
- We have taken away the function of the foot – “Feet are deconditioned, places greater demands on other structures”
- Performance with GLOVES ON!! – STRONG FEET ARE HEALTHY FEET
- 5% of the BF people
- Check out her website!!! spauldingrehab.org
- Treadmill vs. road running is remarkably similar
- Set-up the track with sensors and with video feedback
PAUL HODGES
Paul Hodges needs no introduction. His impact in understanding pain and the effects of pain are paving the way to improved clinical practice. There is no such thing as pain receptors. For interested readers / clinicians please read Lorimer Moseley, (Bio) and the amazing team at the University of South Australia.
Here are some you tube videos that will bring you up to speed on this important topic!
http://www.youtube.com/watch?v=gwd-wLdIHjs
Patrick Wall – different definition of pain
No such thing as pain receptors
Noception input is not linearly related to the amount of pain
No system functions as a simple input / output system
SMART ET AL
Everyone respond differently not as consistently as we would be believe – different solution
FAT PAD exquisitely painful
Principles of Adaptation of – review
Muscle activation may be able to effect the cytokines – therefore the inflammatory response
Myth Busters Session
This was one of the best panel discussions sessions that I ever attended. Moderated by Jenny McConnell – who knew how to push buttons J. It was lively and very heated at times. The panel was star studded, making their comments more potent. Amazing, amazing, amazing. If you can get your hands on the video I would highly recommend it.
Questions:
- Patellar Compression a diagnostic test for PF Pain – good, bad or ugly?
- What is the role of the VMO – does it actually exist?
- SLR – Good, Bad or Ugly? What about with hip rotation?
- Weight bearing or non-weight bearing exercise – when, where & why?
- What about isokinetics – good, bad or ugly?
- Squeeze Ball wall exercise – good, bad or ugly?
- Does bracing make muscles weak?
- What about Tape?
- Can the patient be over reliant on tape
- Kinesiotap – good, bad or ugly?
- Barefoot running – pros and cons
- Should we change everyone’s running mechanics even if they are asymptomactic
- What about clam exercises for hip good, bad or ugly?
Patellar Compression a diagnostic test for PF Pain – good, bad or ugly?
- Michael: compression is not a very good test, but there is tradition. It is painful in asymptomatic painful – 97%. Used often in emergency room setting – UGLY
- Eric: Follows Michael – UGLY. Low sensitivity. Need to include in publishing papers otherwise it is often returned. NOT helpful clinical
What is the role of the VMO – does it actually exist?
This was a beauty of a talk!! At times it felt that Chris Powers was a lone gun slinger – thankfully he held his own.
- Chris: The VMO exists. It’s not a separate muscle from the Quadricep nor can it be preferentially activated and trained. Now what is the relationship of the VMO and the etiology of PFP (despite it’s use clinical). The relationship with PFP is more related to the proximal hip factors that control against internal femoral rotation – Track moving underneath the train. Patella is anchored to the tibia via the patella tendon. Does not believe you can strengthen the VMO preferentially and it is not relevant for PFP. It is the effected by PFP – atrophy
- Paul: When it is compromised because of Pain it can further exacerbate PFP symptoms. Suggests that VMO can be activated separately therefore trained (provides neurological explanation) – there is a subpopulation that can control the VMO preferentially.
- CHRIS: are we treating the effect or the cause?
- PAUL: I missed his great response but it’s something like…”Are we missing something that is a factor in the persistence of the problem??”
- …
- JENNY: Fat pad pain is retropatellar
- ERIC: Few prospective studies of VMO (n = 400) is a predisposing factor for PFP – timing deficit.
- …CHRIS fired back with some great jabs back… (I wish you were there) he questioned Eric if he tested hip function. Eric said NO…
- Chris to Eric: can you sufficiently change tracking with VMO activity??? Jenny said what about pressure changes.
- NAT: if you change internal femoral rotation you change the function of the VMO
- IRENE: Timing is very important in the function of the knee and VMO timing is an important factor.
- Jenny: Is there a timing problem in the HIP
- CHRIS: absolutely….(but what is the cause of the problem)
- PAUL: Kay Crossley 02– there is an association between improved VMO timing and PFP pain
- CHRIS: There have
SLR Good Exercise? What about with Hip Rotation
- Michael: Staple for many years and we’ve improved since.
- PAUL: why would you do a SLR – is it related to function??? Need to address the features of a movement that you need to modify.
- CHRIS: people do it because there is minimal pressure on the knee when extended but this is not true because of quad contraction elicits high patellar stress retropatellar. Terminal Knee extension is not tolerated in PFP patients. Why are we using it??
- ERIC: it is still being used because it is easy to perform.
Weight bearing exercise vs. non-weight bearing
- IRENE: Closed Chain ASAP…because we are trying to get to be in the same environment as it will function. Use Open early but quickly progress
- ERIC: in PFP weight bearing improved sig. vs. non-weight bearing in his study…agree to progress to Wt.bearing ASAP.
- CHRIS: Doesn’t think he use non-wt….Adductor Magnus and Hamstrings are internal rotators and when they activated cause an increase in internal rotation.
- QUAD dominate pattern
- PAUL – distorted the perception (vibration, mastoid process) and perform a point task you will distort performance vs. neutral
- PILATES is an absolutely tragedy – Stiff is not GOOD. We need to modulate properly for the task at hand. Balance between stiffness and
- IRENE: develop proximal stability before distal mobility
What about isokinetics – good, bad or ugly?
ERIC: Provides information and you can train at high speed with relatively low load, and compressive penalties???
CHRIS: Doesn’t use it…maybe for testing never for training.
Squeeze Ball wall exercise – good, bad or ugly?
- Chris: Against it because it activates the hip adductors. And the artificial position that preferentially activates the quads
- PAUL: just because you’ve activated the muscle doesn’t mean that is good or that it makes it function better. It doesn’t exclusively means it valuable
- Need to use fine wire EMG
Bracing makes people weak?
- Michael: Short answer: NO. Long Answer is HELL NO. (Soft brace in the knee) At the ankle it will atrophy
- Chris: No difference between a brace and without a brace EMG…(short term vs. long term) that does not limit motion. But braces that limit motion have the potential to cause atrophy.
- IRENE: Clinical perspective when you take away support (i.e. in the foot) you will increase strength by increasing demand on muscle. It depends on the type of bracing…Neck Brace for 5 years would be tough to extend your head from a flexed position.
- JENNY: neoprene sleeve for LBP???
- PAUL: It will help with Proprioception…Cholewicki answered why wt. lifting athletes want to use a brace — it helps them activate / stability differently.
- ERIC – bracing doesn’t help proprioception without the brace (no Carry-over)
What about Tape?
- Chris: Tape helps reduce pain. In the patella, contact area increases, stress goes down.
- PAUL: will change timing and activation of muscles….just because you’ve decreased pain it doesn’t mean motor coordination will change
Barefoot Running – Pros and Cons
- IRENE: If you run you can run barefoot
- CHRIS: is running BF the only way to reduce the factors associated with running?
- IRENE: Yes…but there are additional benefits of BF
Should we change everyone’s running
- IRENE: if it isn’t broken don’t fix it was the old mantra…but with more prospective data (Hip adduction and link with PFP) but she softening her stance…but kids is a different story
- CHRIS: same effect with forward trunk inclination as BF running
- IRENE: FF increase knee flexion with decrease rate of loading
