Introduction
Patellofemoral pain syndrome (PFPS) is the single most common condition seen by sports medicine practitioners.1 There is extensive literature investigating the efficacy of physical interventions for this condition,2 however there is relatively little considering the role of Acupuncture. This would be in contrast to knee osteoarthrosis which has been well investigated over recent years.3 In this case study an Acupuncture based approach was used to treat PFPS. What has been highlighted are the limitations of Acupuncture treatment if perpetuating factors are not adequately considered and addressed.
Presenting complaint
M complained of regular intermittent knee pain which was localised to the right supero-lateral aspect of the patella. He reported a VAS of 5 on the day of assessment. He also reported the same area as being tender to local pressure. Aggravating factors would be walking for 10 minutes or longer, climbing stairs, sitting with the knee flexed greater than approximately 80 degrees and any attempt to run. Rest and maintaining the knee in extension would ease the knee. Occasionally at night, if he were to roll onto the right knee, pain would wake him. Morning stiffness would be common. He noticed mild swelling around the lateral patella which would worsen towards the end of the day depending on how active he had been.
History
M is a 17 year old scholar who plays provincial rugby and hockey. While playing hockey he sustained a direct blow to the lateral aspect of the right knee by a hockey ball travelling at high speed. There was immediate pain and swelling however he continued to play the remaining ten minutes of the match. The match was followed by a four hour bus ride home that evening during which the right knee remained flexed for most of the time. This aggravated the knee further, worsening the pain, swelling and stiffness.
Over the following five days the pain and swelling was very slow to settle despite regular icing and the use of anti-inflammatory medication. M visited a local hospital where ‘bone bruising’ was diagnosed and was told he required rest. An X-ray ruled out any fracture.
He continued to rest the knee, however after two months he was still very painful. He had been unable to take part in any sport or exercise and so decided to attend physiotherapy.
M’s past medical history included intermittent right anterior knee pain. He had sprained his right ankle on one occasion which settled without intervention. He was otherwise in good general health and was not at the time of assessment taking any medication.
Examination
In standing, a functional squat test revealed an increase in antero-lateral knee pain at approximately 60 degrees of flexion following three repetitions. During the test an increased genu valgum and femoral anteversion could be observed, more apparent on the right which may have been related to gluteal muscle insufficiency.
While positioned in supine a mild effusion over the lateral patella could be observed. There was observed atrophy of the quadriceps muscles, particularly the vastus medialis and some discolouration (redness) of the lateral knee. In a static non weight bearing position there was no abnormal femoral or tibial rotation and the patella appeared normally aligned on the front of the knee. With the knee in extension, on static contraction of the quadriceps there was lateral excursion of the patella with some mild pain associated.
On palpation there was tenderness along the supero-lateral border of the patella and over the lateral quadriceps tendon insertion. A mild increase in skin temperature was also noted. Tenderness was also present laterally over the patellar retinaculum and along the lateral patellar border. Familiar pain could be elicited when the supero-lateral pole was compressed against the underlying femoral condyle (compression test).4 Passive motion testing revealed a restricted medial excursion of the patella.
An examination for trigger points (TrP) revealed taut bands containing active TrP’s within upper rectus femoris muscle and vastus lateralis muscle, both with a vague familiar pain referral to the knee on palpation.
Impression
Based on the given history and basic clinical examination it was decided that PFPS involveling the supero-lateral facet and related structures was the most appropriate diagnosis. The pain was likely to be arising mainly from the peripatellar synovium as is often the case in the absence of obvious joint cartilage damage5, however some degree of ‘bone brusing’ due to the direct trauma may also contribute. Sympathetic hyperactivity has been implicated in the pathophysiology of PFPS4 and may explain the slight increase in skin temperature and discolouration. Furthermore there was tenderness in the associated soft tissue structures such as the quadriceps tendon insertion and lateral patella retinaculum. Active TrP’s found in the upper rectus femoris and vastus lateralis may also be contributing to M’s pain, as well as causing impaired function of the quadriceps muscles.6 At this stage little attention had been given to assessing other potential biomechanical contributing factors which are often associated with patellofemoral pain syndrome.7
Treatment Plan
The use of acupuncture aimed at reducing anterior knee pain8, 9 and improving function was planned. As such it was decided to use three local points at areas of tenderness along the superolateral border of the patella. Distant acupuncture points with a myotomal segmental innervation shared with that of the knee (ST36, SP9 and SP10) would also be used. Acupuncture is effective for reducing symptoms associated with the presence of TrP’s10,11 therefore the active TrP’s located in the upper rectus femoris and vastus lateralis would be included.
M had not received acupuncture previously. A full explanation of the nature of the technique was given including the possibility of minor adverse reactions following treatment. These may include an exacerbation of symptoms, bruising, sedation or dizziness. More serious adverse events such as infection were explained to have a low incidence12 and the risk could be minimized by using sterile disposable needles as well as following standard hygiene practice at all times. The relevant anatomy in relation to each point being needled would also be considered from a safety point of view.
Once the optimum dose had been determined (i.e. the maximum level of sensory input to the central nervous system without causing aversive pain or significant reaction), a minimum of four sessions would be given to determine responsiveness. If the dose needed to be increased this would be achieved by increasing the duration and/or level of manual stimulation. Treatment would be on a weekly basis. If there was no symptomatic improvement with associated improvements in function after four sessions with at least three at the optimum dose the treatment approach would be revised.
In addition, gluteal and vastus medialis muscle strengthening exercises would be prescribed.1
The main outcome measures included pain levels on the VAS, as well as the number of pain free repetitions on the functional standing squat test. General levels of activity, pain free walking duration and the ability to climb stairs would also be taken into consideration.
Vinco (25mm X 0.22mm) needles would be used unless otherwise stated.
Treatment and results
Session 1: M was positioned in supine with his right knee slightly flexed over a rolled towel. When comfortable the following points were needled:
ST36: The needle was inserted to a depth of 1.5cm into tibialis anterior. A comfortable de qi sensation was reported. No added manual stimulation was applied. Deep penetration at this point was avoided due to the presence of the underlying anterior tibial vessels and deep branch of the common peroneal nerve.
SP9: The needle was inserted to a depth of 1.5cm. A comfortable de qi sensation was reported. No added manual stimulation was applied. Deep penetration was avoided due to the presence of the posterior tibial vessels. Branches of the saphenous vein which could be seen were avoided.
SP10: The needle was inserted to a depth of 2cm. A comfortable de qi sensation was reported. No added manual stimulation was given.
After 5 minutes three needles were inserted along the superolateral border of the patella at the points of maximum tenderness. These points coincided with the insertion of the quadriceps tendon and lateral patella retinaculum. The needles where inserted to a depth of approximately 0.5cm while avoiding penetration of the patellofemoral joint space. While the under surface of the superolateral pole of the patella was also likely to be tender, it was not attempted to needle this area for risk of introducing infection to the joint. Again a local de qi sensation was reported.
After a further 10 minutes the needles were removed and disposed of in a sharps box. M had found the de qi sensation strong but not unpleasant for the duration of the treatment.
The TrP’s located in the upper rectus femoris and vastus lateralis were then needled. Insertion was to a depth of 2cm. This was followed by further manual stimulation in the form an insertion and withdrawal technique13 resulting in a local twitch response on each of the 3-4 withdrawals and re-insertions into the vastus lateralis but not the rectus femoris. Needle depth was limited to 2cm due to anatomical considerations in the region of the femoral nerve and artery underlying the TrP in rectus femoris.
Following treatment, no adverse reactions were reported. M was advised to moderate his activities, such as walking to within his pain limits. Gluteal and vastus medialis muscle strengthening exercises were prescribed.
Sessions 2-4: No adverse reactions were reported following session 1, with only mild treatment soreness lasting a few hours post treatment. It was decided to repeat the treatment above for a further three sessions, while increasing the level of stimulation in order to maintain an optimum dose. The duration of treatment was increased such that ST36, SP10 and SP9 remained in situ for 20 minutes, and the peri-patellar points for 15 minutes. Further moderate manual stimulation was applied using a rotation technique every 3-4 minutes to maintain a strong but non aversive level of de qi. The needles were removed and followed by needling of the TrP sites, again with a lift and thrust technique applied. At no point did treatment soreness last longer than 3-4 hours, nor was there any other adverse reaction post treatment.
Session 5: M would experience some pain relief post treatment for approximately 48 hours however this was unsustained. By session five, having received four sessions at what was considered optimum dose his VAS had remained unchanged at 5. Furthermore the number of pain free repetitions on the functional squat test had only improved by two. He still had to limit his walking duration and found stairs difficult. There had been some improvement in discolouration and skin temperature.
It was decided at this point to refer M to a sports physician for an opinion. The report to follow suggested prescribing a pair of ankle and foot motion controlling orthotics to correct a tendency to over-pronate which was considered to be contributing to his tendency towards excess genu valgum and femoral anteversion during the squat test. This occurred bilaterally but was more evident on the right. This was considered by the sports physician to be a pain perpetuating biomechanical factor.
An appointment was arranged with a chartered physiotherapist specialising in biomechanics who arranged for pair of casted orthotics to be made. Once fitted and in combination with further acupuncture on a weekly basis, significant improvements were made.
Sessions 6-9: A further four sessions of acupuncture treatment was applied. The total duration remained at 20 minutes with an optimum dose maintained by adding manual needle stimulation. This was in conjunction with a progression of the gluteal and vastus medialis muscle strengthening exercises.
Session 10: At this stage the VAS was an intermittent 1. The tenderness along the superolateral border of the patella had reduced significantly, along with minimal pain on compression of the patella. Tenderness at the TrP sites was minimal and no referred pain was evoked. M was able to perform up to 15 functional squat repetitions with no knee pain. Walking longer than then minutes and stair climbing was not longer painful. At this stage the acupuncture treatment was discontinued in favour of further monitored exercise rehabilitation over the following four weeks which allowed him a full return to sport.
Discussion
Acupuncture has been used to successfully treat PFPS based on the use of an individualized treatment approach.14 However this condition often presents with contributing biomechanical factors which need to be addressed if successful outcomes are to be achieved.7 This case study highlights the need to properly diagnose a condition and also identify predisposing or perpetuating factors. In this case study, M had a tendency to over-pronate at the subtalar joint of the ankle. When corrected a reduction of PFPS symptoms has been achieved.15 This was overlooked on initial assessment and had it not been identified is likely to have resulted in a poor/non responsive outcome. Once M had received his orthotics and the biomechanical strain to the knee reduced he became more responsive to the use of acupuncture.
Effective treatment of TrP’s is also dependant on identifying and addressing predisposing factors.16 A reduction in local sensitivity, referred pain and an improvement in muscle tone was achieved following acupuncture treatment of TrP’s in the quadriceps muscle in this case. Hopefully having addressed the biomechanical factors, the chance of recurrence will also have been reduced.
A systematic review17 evaluating the effectiveness of acupuncture in treating chronic knee pain concluded that it was significantly superior to sham and to no additional treatment. However as a result of the heterogeneity of results, further research is necessary to confirm these findings. This is likely to be due to the heterogeneity in test subjects in the first instance. As this case study suggests, remote factors can have an influence on the outcome of acupuncture treatment and provides further argument in favour of detailed assessment and sub-classification in clinical trials.
References
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