Introduction

Lower back and upper buttock and leg pain (LBP); have been attributed to pathologies associated with the lumbar disc, facet joints, piriformis muscle, sacroiliac joints, and cluneal nerves. The literature has described a plethora of pain management strategies, including bed rest, with or without pain medications or anti-inflammatories, nerve blocks, radio-frequency ablation, chiropractic manipulations, along with various massage doctrines including arthroscopic cluneal nerve release. The development of magnetic resonance imaging over the past 42 years and more recent innovations in diagnostic ultrasound have boosted our understanding of pathoanatomical changes which can affect the low back and upper buttock. The knowledge gained however has not always been used wisely and responsibly.

It was in 1972 that the first MRI was used to visualize a mouse thorax. Prior to the advent of MRI and CT in the 1950s lumbar x-rays were the only imaging available to help out with the diagnosis. These only showed some of the soft tissues alignment, and arthritic changes in the spine. In 1934 Mixter and Barr had published the first paper linking the herniated disc to sciatica and it was largely believed that the lumbar disc was the main pain generator of low back pain and referred buttock and leg pain. However, diagnosis of disc herniations in those days could only be accomplished by lumbar myelograms, which were wrought with complications and side effects and were usually reserved for surgical planning. The procedure itself was quite unpleasant for patients, consisting of a lumbar puncture, in which an oil-based dye was then injected into the epidural space. Some patient suffered extreme pain from the procedure, while one in ten patients suffered dural puncture short-term headaches. Thousands were subjected to a lifetime of crippling pain due to arachnoiditis, caused by the oil based contrast agent.

It wasn’t until the 1980’s that the first non-invasive diagnostic imaging modalities of CT (Computer Tomography) an MRI (Magnetic Resonance Imaging) became more widely available as a tool for diagnosing the cause of low back pain. With them it was possible to see a wide variety of potential pain generating pathologies, such as disc herniations, disc degeneration, end-plate Modic changes, and the high intensity zone (HIZ) manifesting annular tears.

However, these new technologies in identifying all of these potential pathologies led to an explosive epidemic of spinal surgery. There was a sharp rise in spinal surgeries that can be traced to CT and MRI availability with audits showing a 10-fold rise in spine surgery in places were these modalities were widely available. In the 1970s the incidence of laminectomy was 10 times higher in the US than the UK, and in more recent times there are 20 times more spine surgeries performed in the US states were MRI and CT are the most available. More recent advancements in diagnostic ultrasound have also identified the cluneal nerves of the upper buttock as potential targets for injection, radiofrequency ablation and arthroscopic release procedures. However, as is the case with lumbar discectomy, even cluneal nerve release surgeries may have a sequela of chronic pain, or nerve-arterial injury. Are these surgeries necessary?

To answer this question one must first examine structure. The human anatomical buttock is composed of a diversity of interacting and interdependently functioning structures. Striated muscle is clearly in abundance. Each of these, however, though anatomically differing in basic structure and function, may selfishly act alone or in concert to precipitously initiate buttock discomfort or outright pain. Intrinsically, direct localized blunt trauma apart, few of these buttock items are capable of producing localized, upper buttock pain whether it be acute, sub acute or chronic in quality.

Referred pain and its often-accompanied palpable tenderness are explained by medical clinical pathologists as an error in perception within the relevant segment of the cerebral cortex. Though not particularly exacting in its content, it serves the purpose of stimulating further appropriate research. Advancement, in medical knowledge, historically, has proven to be not always rapid. Most unfortunately, referred pains with or without accompanying referred tenderness emanating from musculoskeletal structures, to this day, is being diagnostically almost ignored despite its irrefutably both clinically and experimentally. This information was first published by Sir Thomas Lewis in London in 1932.(1)

Lewis, an accomplished cardiologist possessed an insatiable desire to understand the obvious and the accepted in medicine yet still inexplicable. Intrigued by cardiac pain being extensively perceived by patients in shoulders, arms and elsewhere in the upper body he began injecting an irritant (6% saline) into specific soft tissues of the lumbar spine and pelvis. His injection produced a most unpleasant poorly defined discomfort at the site of the injection and a reproducible, clearly defined nerve-like pain, extending down the ipsilateral lower limb. This enlightenment provided Physicians with an alternative understanding of bodily structural pain causation and its extension for long distances within the human body other than radiating down nerves. Comprehending a soft tissue structure located for example, within the buttock area, without reliance on nerve radiation, producing pain similar in character to a nerve, extending from the buttock down the posterior thigh and calf to a certain predictable area of the ankle or foot was almost unbelievable. This information changed the understanding of pain production and its perception within the human body forever.

Diagnostic and therapeutic differentiation of radicular nerve pain from non-dermatomal mechanical referred pain is essential. Frequently low back and upper gluteal pain is accompanied by well-defined lower limb pain. The pain pattern may mimic sciatica with the lower limb pain being the most severe of all. In today’s surgical world, a damaged intervertebral disc is usually held accountable for the causation of persistent or acute back and leg pain.

The joint between the last spinal vertebrae and the sacrum by its associated ligaments and muscles forms a very strong yet mobile union allowing active spinal flexion and extension movements. Active lateral flexion especially near its full range of flexion is comparatively limited by the intrinsic construction of the lumbosacral joint, its ligaments and associated muscles. Active rotations at this joint suffer similarly as lateral flexions.

The Importance of the Gluteus Medius Muscle in Unilateral Buttock Pain

The degree of active lateral and rotational movement is largely controlled the Gluteus Medius muscles one located in each buttock. The main function of these two gluteal muscles, by their contraction, enables a flexed body to regain its upright posture. The bilateral Gluteus Medius muscles are ideally located, on contracting, to restore a flexed body to its usual semi-straight, upright posture. They arise from the flat outer surfaces of the Ilium between its superior and middle curved lines, from a portion of the outer lip of the crest of the Ilium and from the strong gluteal aponeuroses. It also forms a strong aponeurotic binding with the thoracolumbar fascia near the Iliac crest. This multi divided, extensive base attachments coupled with a broad muscle belly increases the functional directional forces available from these muscles to control the various angled directions required by a flexed trunk of the human body. The individual, contractile muscle fibers of the Gluteus Medius muscle rapidly converge into the apex of a triangle, forming a strong tendon to be inserted into the lateral facet of the greater trochanter of the femur. The muscle is unique among the gluteals in that it tapers downward at a steep angle parallel to the hip. However, this unique orientation renders the fibres of the broad-based origin of the muscle at the iliac crest prone to sprain, particularly with lumbar movements which couple forward flexion with contralateral side bending.

The nerve supply of the gluteus medius is from the fourth and fifth lumbar nerves. As striated muscle is weakest when fully extended, coupling of forward bending with lateral flexion most often damages this muscle. Damage occurs whenever a muscle is demanded to an exertion it has not ever done before or is not prepared for this particular exertion. It also becomes damaged if asked to do something well within its tolerance for too long a time period. In regard to mechanical pain, the mass of the buttock consists of striated muscle abnormalities. Functional testing of the gluteal musculature can determine the pain generator, providing a logical foundation for targeting regenerative injections into both deep and superficial structures.

One must not however, perform regenerative injections as an isolated treatment. Comprehensive prolotherapy of the lumbar, pelvic and sacroiliac structures may also be required. Exercise and movement are essential components of healing, and patients immediately post proliferative injections, must begin range of motion movements to ensure healing occurs under full range of motion.

The poke and prod method of diagnosis for determining if gluteus medius sprain is responsible for upper buttock pain lacks specificity and this method alone may lead to erroneous diagnosis of cluneal nerve entrancement. However, by actually testing the gluteus medius muscle for comparative bilateral strength and pain reproduction, the physician can readily clarify the diagnosis and avoid improper treatment.

This approach of stimulating healing in the ‘presence of full range of motion’ goes against the grain of conventional management’s rest, it offers a more effective and rapid healing without disuse atrophy and scar tissue formation caused by rest.

Methods of Diagnosis and Treatment

The gluteus medius is identified as the pain generator by careful history, and exclusion of other potential causative factors. Dynamic gluteus medius muscle testing is employed confirming diagnosis. (See Figure 1.) Further pain-relieving diagnostic blocks along the gluteus medius enthesis at the inferior margin of the iliac crest, provide diagnostic verification. Injection of the entire enthesis is achievable with a 22-gauge 90 mm spinal needle through a single point of entry. (See Figure 2, black dots.) Larger patients may require additional primary entry points medially and laterally to ensure comprehensive treatment of the entire aponeurotic origin. Once the needle has penetrated subcutaneously, the needle tip is redirected to touch bone repeatedly, with injections of 1 cc of biological regenerative solution at multiple points (See Figure 2, red dots.) along the inferior margin of the iliac crest. Distal insertion treatment is directed to the lateral trochanteric facet. Total injection volumes range between 10-20 cc of solution, and are also dependent of patient size. (See Figures 2 & 3.)

As the aim is healing in the presence of full range of motion, Mayo belts and other back braces that limit full flexion of the lower are not recommended. High BMI patients may benefit from weight loss and the wearing of constrictive clothing and belts should be avoided.

There may also be recreational, sport or occupational risk factors. Weight lifters, builder or other tradesman may wear tool heavy belts for prolonged periods, or police officers, who must continually wear utility belts laden with handcuffs, radios, pistols, ammunition clips while sitting or repetitively getting in and out of vehicles may be vulnerable. The author’s approach to managing upper buttock pain is to have the patient commence range of motion exercises immediately following injections. The patient will sit in a hard-backed chair. While keeping feet flat on the floor, the patient bends forward attempting to reach the floor with their fingertips. May sure to advise the patient to keep the chin tucked towards the chest when forward flexing. (See Figure 4.)

Another exercise is standing leg swings. Keep the knee bend at 90 degrees and swing the hip into extension while keeping the buttock muscle contracted. Both the seated forward bends and standing leg swings should be repeated 15 times at least twice per day. (See Figure 5.)

Discussion

Nuances and meanings of these terms such as trigger points (TPs) and tender points are inconsistently defined, with diagnosis confined exclusively to history and physical examination. (2) Furthermore, the hallmark physical features of tender points, taut muscle bands, and characteristic pain reproduction and referral have poor inter-rater reliability.(3,4) Recent Delphi panel consensus of 2 of 3 diagnostic TPs criteria (taut band, hypersensitive spot, referred pain), have made progress though, agreeing delineation between active and latent trigger TPs, will be useful in establishing evidence- based definitions.(5)

However, the current myofascial pain syndrome model for which cluneal nerve injections, radiofrequency and the need for surgical nerve release is based, and which solely relies on ‘trigger point’ palpation does not take into account other potential pain generators. Case in point would be Hilton’s law, which states that a nerve supplying a joint, also sends innervating branches not only to the muscles and enthesial attachments that move that joint, but into the skin overlying the joint as well.(6)

Medial branches of the cluneal nerves may also be responsible for so-called pseudo-sciatica, when they become entrapped in transit from the thoracolumbar fascia and over the iliac crest. It has been proposed that cluneal nerve entrapment may mimic sciatic symptoms of low back pain with referred pain into the posterior thigh, hamstrings, calf and on occasion the ankle and foot.(7)

However, without a Cyriax approach, lumbo-sacral ligament laxity, referred nerve pain for deeper structures (facet and sacro-iliac joints), or physiological-embryologically normally tender points may be missed or misinterpreted. In regard to the latter, examiners would be therefore be advised avoid overzealous palpation pressure in the upper gluteal region.

Proliferent injections offer such a solution, as these injectants, utilizing substances such as dextrose, dextrose-glycerol-phenol targeting the gluteus medius enthesis will stimulate natural healing processes through inflammation.

Accurate injection delivery to the gluteus medius enthesis requires an in depth practical knowledge of anatomical landmarks and palpation skills. Some clinicians may also be performing these techniques under ultrasound or fluoroscopic guidance.

The author had noted that when first treating low back and upper buttock pain in the early 1960s, that dextrose was only a 10% concentration in the Sclerosant was difficult to obtain. Be reformulating, and adding 50% dextrose to the solution a highly effective regenerative solution was achieved. This concentration worked very well for gluteal pain, with the phenol quelling the cluneal nerves in an almost pain free treatment. Other solutions, such as those used by George Hackett such as the psysillium seed oil-Sylnasol, produced very painful side effects, which limited patient compliance.

Conclusion

Accurate diagnosis of upper buttock pain is not achievable by tender point palpation alone. Comprehensive structural and functional examination including muscle testing for gluteus medius pain & weakness, and exclusion of lumbo-sacral ligamentous instability are essential to determining buttock pain causation. Correct diagnosis is then proved by infiltration with local anaesthetic. Scans may be performed to exclude other existing problems. However, managing the patient according to clinical findings and response to treatment render imaging of secondary importance.

‘Bongling’ of the gluteus medius enthesis at the iliac crest, defines a process of serially injecting regenerative solution to both deep and superficial structures coupled with rehabilitative exercises, This approach of managing upper buttock pain offers a more effective, comprehensive and permanent restoration of function and should be considered as a first line management. This approach offers an alternative and potentially more effective management than stand alone prolotherapy, other injections, and nerve-release surgeries.

Acknowlegements

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Many thanks to Dr David Luna Gonzalez MD, Raquel Perez Nieto, Chief of Staff of the Ongley Institute, and Rosilinda Chang Huang, Institue Administrator for your support and friendship through the years, and in fond memory of Dr Milne ‘Bud’ Ongley, September 24 1924 – 03 January 2020. Physician, Inventor, Teacher, and Friend. Hail and farwell.

References

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Resources for general public:

• Diagnosis or missing diagnosis of Deep gluteal syndrome: Typically doctors do not diagnose Deep gluteal syndrome initially. They may call it other things like piriformis syndrome or sciatica, which may contribute to significant hip area pain. You may ultimately get the diagnosis of Deep gluteal syndrome if you display pain and numbness in your buttocks that radiate into your leg if initially this was not confused with problems of lumbar stenosis, or Sacroiliac Joint Dysfunction, ischiofemoral impingement, hamstrings, and pudendal nerve entrapment among the list of other possible causes. Another problem that may be difficult to identify is that you have multiple issues, Deep gluteal syndrome may in fact be only one of the problems causing your pain.
• Comparing Gluteus Medius Tendinopathy Injections and Surgery: In February 2020, researchers publishing in the Journal of physical therapy science summarized the connection between hip, back, leg and knee pain under the Gluteus medius syndrome umbrella and how easily a Gluteus medius syndrome or tendinopathy can be missed or thought of as something else: