By: Kathy Berglund, DScPT, FAAOMPT, COMT, OCS, ATC

Commentary on: Bennell K, Egerton T, Martin J, et al. “Effect of Physical Therapy on Pain and Function in Patients With Hip Osteoarthritis: A Randomized Clinical Trial. JAMA. 2014;311(19):1987-1997.

The purpose of this article claims to assess the effects of physical therapy on pain and function in patients with hip osteoarthritis, finding no difference between the group that received physical therapy and the control group.  The study followed proper research protocol so as to be included as a randomized control trial with an n=102 and 83 completing the entire study time frame.  Subjects were randomly divided into two groups with one group receiving physical therapy and the other a sham treatment.  In looking more closely at the physical therapy intervention, the patients were followed over a 12 week period being seen twice the first week, once a week for the next 6 weeks and then once every 2 weeks for the remaining 6 weeks.  The first physical therapy sessions were between 45 minutes and an hour while the remaining sessions were 30 minutes.

The protocol was only semi-standardized and consisted of manual therapy thrust manipulation to the hip, mobilization to the lumbar spine, myofascial mobilization, stretching exercises and 4-6 strengthening exercises to be performed 4x per week at home by the patient for the hip abductors and quadriceps along with balance exercises.  During the 6 month follow up period the patients were not seen in physical therapy and were supposed to be performing unsupervised home exercises 3 times per week. 

Analysis of this protocol for physical therapy for hip OA brings to light some major flaws in the study design.  There is no mention of specificity of muscle testing or exercise prescription in this study.  It is assumed that patients with hip osteoarthritis complaining of pain greater than 40mm on a 100mm visual analogue scale (their inclusion criteria), would present to physical therapy with significant impairments in muscle performance.  These impairments would include the musculature of the hip girdle and possibly the core muscles of the pelvis and trunk as well. 

Pain in a joint will affect many of the components of muscle performance around that joint with precise motor control often being the first component that fails. Motor control is produced by a precise relationship between the inert structures, the contractile structures and the neurological system, producing timely and effective control of joint motion.  Proper motor control of the pelvis and hip girdle is imperative for proximal stability prior to extremity mobility, with a loss of motor control creating aberrations in the arthokinetmatic pathway of the joint leading to what Panjabi termed a “loss of neutral zone” (Panjabi, 1992).  Precise assessment of the motor control of the hip musculature, specifically the external rotators and hip abductors is critical when evaluating someone with hip pain.  In fact, assessment of the motor control of these muscles has been used to predict future injury to the lower extremity (Leetun et al, 2004).  There is no evidence in this study that motor control was evaluated or treated specifically.

Following restoration of precise motor control the next muscle performance parameter that should be assessed is muscle endurance (Kisner and Kolby, 2012). Muscular endurance enables exercise to continue for long periods of time while maintaining proper body mechanics and posture (Fahey, Insel & Roth, 2009). Since walking is the primary function of the lower extremity, the external rotators, abductors and extensors need adequate endurance to maintain painfree ambulation throughout the day, not to mention handling the variety of functional loads such as stair climbing or carrying objects. 

Two prominent organizations, the National Strength and Conditioning Association (NSCA) and the American College of Sports Medicine (ACSM), have similar recommendations for improving muscular endurance.  Specifically, the NSCA advocates completion of 12 or more repetitions at less than 67% of a one repetition maximum (RM) load, with two to three sets and 30 seconds or less of rest between each set (Baechle & Earle, 2008). The ACSM recommends a similar program for muscular endurance, prescribing 15-25 repetitions at 50% 1 RM utilizing 3 sets and similar rest periods (Thompson, 2009).  There is no evidence in this study that these precise parameters were followed for the physical therapy group subjects. Furthermore, since all subjects had painful hips it is most likely that the critical muscle groups (external rotators and abductors) were so impaired that the subjects would not have been able to perform precisely dosed exercises at home, as just the weight of their limb itself most likely exceeded either the 67% or 50% of 1RM needed for improving muscular endurance.  Muscle parameters will only change when a specific demand is placed upon them and once specifically dosed, muscles must be trained 3 times per week to achieve results.  Furthermore, the muscles must be retested every 2-3 weeks and re-dosed accordingly to continue increasing their performance over time (Baechle & Earle, 2008).

Lombardi et al (2008) conducted a randomized control study analyzing the use of specifically dosed resistance training in patients with long term shoulder pain.  Sixty subjects were divided into 2 groups with one group receiving precise exercise testing and dosing and the other group being placed on a “waiting list” (ie not exercising).  Subjects in the exercise group had their shoulder flexors, abductors, internal and external rotators specifically tested and then dosed for exercise using a 50% and 70% of 6RM protocol.  Subjects exercised 3 times per week and were re-tested every 2 weeks for 2 months.  A statistically significant difference was found with improvements in pain and function for patients in the experimental group compared to the control (P < 0.05).

 Mangione et al (2010) conducted a study comparing specifically dosed exercise versus a control group for 26 subjects following hip fracture.  The control group applied TENS along with guided imagery for treatment, whereas the experimental followed a home based exercise program for the hip extensors, abductors, knee extensors and plantar flexors of the foot.  These muscles were selected due to their role in gait and transfers.  Even though the exercises were performed at home, specific dosing based on an 8RM evaluation was given and the patient performed the exercises 3 times per week.  Subjects in the exercise group were also re-dosed every 2 weeks.  A significant difference was found between the exercise group and the control group using the modified Physical Performance test (p=.001) one year post hip fracture.

The success of the exercise groups in the above mentioned studies ultimately depended on the specificity of the physical therapy intervention.  In the discussion portion of this hip OA study, the authors state “The active physical therapy program may not have adequately targeted and changed physical impairments, such as muscle weakness and restricted range, that are associated with hip pain and dysfunction.

Participants may not have performed the home program to the same intensity as a supervised program. “  Furthermore,  the authors  go on to reveal that a systematic review evaluating the effect of exercise on knee osteoarthritis demonstrated that the more frequently the patient saw the physical therapist, the better the outcome.

Thus, the authors statement of “it is not known whether a whether a more intensive protocol may have been more effective than sham treatment” should be highlighted and in bold script. Basically what this study has shown is that the current model of healthcare, where patients with musculoskeletal pain and significant dysfunction are seen infrequently and given non- specific and unsupervised exercise programs, does not work.  It is increasingly difficult to get healthy persons to exercise 3 times per week as evidenced by the rising rate of obesity.  Why is it, in this age of evidenced based medicine, that the healthcare system thinks that patients in pain with limited range of motion and large muscle performance impairments, will actually be able to successfully correct these problems at home with no specific equipment or supervision? 

As a new physical therapist in 1978, patients were able to see the physical therapist 3 times per week for as long as 2-3 months depending on the diagnosis.  Manual therapy care thus could be consistently performed over a period of weeks.  Furthermore, physical therapy education emphasized therapeutic exercise heavily in the curriculum at that time so clinicians were using more exercise physiology principles in evaluation and treatment of muscle impairments.  At the 2011 World Physical Therapy Confederation meeting, a panel of physical therapists and exercise physiologists examined the current role of precise exercise testing and prescription among physical therapists.  Their conclusion was that evidenced based practice with regards to exercise testing and prescription may now be under- utilized in PT practice.  Causes such as reduction in adequate curriculum in this area in PT school due to the increases in specialized topics, healthcare cost limiting patient visits and less time spent with the patient were pointed out (Moffat et al, 2012).

The North American Institute of Orthopaedic Manual Therapy (NAIOMT) has stood firm in maintaining a stance supporting specificity in manual medicine as the test/re-test evidence for non-specific manual techniques has been published.  NAIOMT does not have short term solutions for pain reduction as its top priority. The research has clearly indicated that many of the techniques physical therapists employ can cause an immediate reduction in the patient’s perceived pain. NAIOMT prides itself on training clinicians to seek out all of the patients specific biomechanical impairments that coalesce together to produce impaired function. The specific NAIOMT examination includes locating the pain generator, assessing the neurological system, locating the specific impairments of joint mobility and stability, as well as, the specific impairments of muscle performance.  Once all of the specific impairments have been located in all of the relevant systems, the NAIOMT clinician is then taught to use sound clinical reasoning, whose foundation lies in the basic sciences as well as the research evidence, to develop a patient specific treatment program. 

As a group, physical therapists need to believe the results of this study, ie that a non-specific multi-modal approach will not improve pain and function in patients with hip OA.  Depending on the loss of joint mobility, specific manual techniques may need to be performed consistently 3 times per week for several weeks.  As the other studies demonstrating the success of specifically dosed exercise programs indicated, physical therapists also need to be specific with exercise testing and prescription.  As a community, physical therapists need to work together to develop methods for patients to perform their specifically dosed exercise programs 3 times per week for as many weeks as it takes to achieve the functional goals.  In my personal clinical experience this may take 8-12 weeks or more depending on the amount of muscle impairment present on the first visit. 

Since physical therapy costs have increased, developing  an affordable cash based system may prove beneficial.  People are paying personal trainers and massage therapists on a cash basis in attempts to “fix” their problems.  Physical therapists need to capture this market as we should be the provider of choice for any musculoskeletal pain problem. Lastly we need to educate referring physicians and patients as to why studies like this prove that physical therapists who use non-specific approaches will not produce the same long term functional outcomes that specifically trained therapists, such as the NAIOMT trained clinician, will produce.