The anatomy of hip is widely complex and several anatomical structures interact and contribute to its functioning. For position and role, hip and the surrounding tendons, which have their insertion around, are overstressed and often overloaded, especially in athletes. This could lead to the developing of several tendinopathies, among which the differential diagnosis is often complicated. Many conservative treatments are used in clinical practice, while actually, no defined conservative protocol is recommended.

This is a review article. The aim of this manuscript is to evaluate the current evidences about the effectiveness of conservative management in hip tendinopathies.

Conservative treatment is effective in the management of hip tendinopathies and may be considered the first-line approach for patients affected. However, there is lack of evidences about which is the most effective treatment. Exercise therapy seems to provide long-term pain relief, but the literature is still lacking about the correct type, dose, posology, intensity of exercise prescribed. Further studies about different local approaches, as PRP or hyaluronic acid injections, may be encouraged.

I.

Keywords: tendinopathy, conservative management, hip, review

The anatomy of hip is extremely complex and several anatomical structures interact and contribute to its functioning. The wide femoroacetabular range of motion is driven by the high number of muscle groups that surround the hip, including flexors (iliopsoas, rectus femoris, pectineus, and sartorius muscles), extensors (gluteus maximus and hamstrings) and smaller muscles allowing for abduction, adduction, and internal and external rotation, as gluteus medius and minimus, obturator externus and internus, piriformis, and quadratus femoris muscles1. There are approximately twenty bursae in the trochanteric area2 and the peritrochanteric space has been well described3. Some bursae may be acquired due to excessive friction4, while three bursae are consistently present in the majority of individuals. These include the gluteus minimus bursa, located anterosuperiorly to the greater trochanter. The subgluteus medius bursa lies deep to the gluteus medius tendon. The subgluteus maximus bursa is the largest and often described as the “trochanteric bursa”. This lies lateral to the greater trochanter between the gluteus medius and maximus. The greater trochanter is a large quadrangular projection at the junction of the femoral neck with the shaft. It is the main attachment for the strong abductor tendons. The gluteus medius and minimus muscles have been referred to as the “rotator cuff of the hip”5. For position and role, the hip and the surrounding tendons, which have their insertion around (mainly in the greater trochanter), are overstressed and often overloaded, especially in athletes6. It is estimated that injuries to the hip or pelvis represent approximately 2–5% of all sports injuries and up to 11% of running-related injuries, while a real incidence of each single condition is not determined yet7. Multiple pathologies often coexist and different tendinopathies can affect the muscles and tendons structures, causing similar symptoms and referred pain to the hip particularly in the trochanteric region8. Several names, in the years, have been given to Greater Trocanther Pain Syndrome (GTPS), as “hip periarthritis” and “trochanteric bursitis”9,10. However, in most cases the diagnosis of trochanteric bursitis is inappropriate, due to that the cardinal signs of inflammation are absent and isolated bursitis is uncommon11. In fact, co-existence of both bursitis and tendinopathy often occurs12. Particularly, GTPS contains a range of causes including gluteal medius and minimus tendinopathy/tears, trochanteric bursitis and external coxa saltans13,14, while the pathogenesis remains not completely understood15. Proximal hamstring tendinopathies (PHT) cause pain in the ischiatic region that may extend to the posterior thigh and are often related to sprinting actions16. It seems that a key factor for the development of PHT is represented by poor lumbo-pelvic control and muscle imbalances with hamstring weakness17. Chronic and recurrent groin pain could be determined by insertional adductor tendinopathies that are frequent in sports involving sudden changes of direction, continuous acceleration and deceleration, sliding tackles and kicking, as in football. The overloading of the pubic symphysis and insertional tendons could be induced by the strength imbalance between the hypertonic adductor muscle and hypotonic large flat muscular sheets of the abdomen18.

Besides, also iliopsoas tendinopathy, internal snapping hip and iliopectineal bursitis could provoke groin pain and the three pathologies could be collectively indicated as iliopsoas syndrome19. While the incidence is not well investigated, an MRI study showed that prevalence of iliopsoas tendon and myotendinous injuries was 0.66% in a large sample of 4862 consecutive hip MRI20. This condition not exclusively affect athletes, but could be secondary to hip arthroplasty and arthritis19.

The complexity of the biomechanics of the hip and the consequent problems of differential diagnosis determine the difficulty for the clinicians to endorse an appropriate treatment protocol. However, conservative treatment should be considered the primary approach, different factors as severity and duration of symptoms, experience of physicians and presumptive diagnosis may be considered.

Several treatments have been proposed and are currently used in clinical practice21:

• - Rest and modification of activities
• - Reduction of the sporting activity
• - Cryotherapy
• - Hot packs (not in acute phase)
• - Oral Medications: nonsteroidal anti-inflammatory drugs, which can relieve pain and decrease inflammation in the acute phase. The intake should be limited to short periods, because prolonged intake may affect tendon healing
• - Physiotherapy: exercises and stretching
• - Resolution of biomechanical abnormalities of the lower limbs (leg length discrepancy, pes planus/cavus)
• - Postural gymnastics
• - Strengthening of hip abductors and external rotators muscles
• - Improving pelvic lumbar control: core stability and pelvic stabilizers exercises
• - Local corticosteroid injection
• - Physical therapies.

The aim of this review is to analyze the different treatments proposed in tendon pathologies around the hip and determine the current evidences in the management.

A comprehensive systematic review of the available literature in the English language was performed using PubMed, PEDro and Google Scholar. It was conducted and reported specifically by defining the study characteristics of interest, information sources, search strategy, selection strategy, data extraction, defining summary measures, and describing the methods of data handling. The selection of the material was concluded in April 2016.

Keywords used were: hip tendinopathy or gluteal tendinopathy or hamstring tendinopathy or trochanteric bursitis or iliotibial syndrome or greater trochanteric pain syndrome and treatment and rehabilitation and conservative management and physiotherapy and shock waves and corticosteroid injections and physical therapy and exercise program and stretching.

Inclusion criteria were: 1) clinical trials of any type about rehabilitation treatment of tendinopathies around the hip; 2) papers published in the past decade; 3) English language; 4) Humans.

Exclusion criteria were: 1) surgical trials; 2) studies whose title and abstract were not related specifically to the search.

All methods used in this study meet the ethical standards of Muscles, Ligaments and Tendons Journal22.

The initial search yielded 330 articles, of which 15 were identified as relevant after screening of titles/abstract. Full texts were retrieved, and 1 further article was added from searching reference lists and citation tracking.

The 16 studies included 4 evaluating treatment in Proximal Hamstring Tendinopathy, 2 in Adductor Tendinopathy, 3 in Iliopsoas Tendinopathy, 1 in treatment of Acute Calcific Tendinopathy around the hip, 5 in Greater Trochanteric Pain Syndrome and Trochanteric bursitis and 1 in Gluteal Tendinopathy (Table I).

Table I Design, follow-up, results and measurements of outcomes of selected studies.

Four studies evaluating conservative management of proximal hamstring tendinopathies were identified. A pilot study and a Double-Blind Randomized Controlled Trial (RCT) focus on PRP injections, a retrospective study evaluates the use of corticosteroid injections and a RCT evaluates the efficacy of Extracorporeal Shock Wave Therapy (ESWT).

Dallaudière B et al.23 enrolled 408 patients treated with a single intratendinous PRP injection for different site tendinopathies, including 40 patients affected by proximal hamstring tendinopathy. The Authors found a statistically significant clinical and US improvement at 6 weeks of follow-up that was not dependent by age, gender and type of tendinopathy. No clinical complications were reported during follow-up.

In a double blind RCT, PRP injections result equally effective to whole blood cell injections until 6 months of follow-up, without any statistically significance difference24.

Zissen MH et al.25 in a retrospective study enrolled 65 patients who received ultrasound-guided corticosteroid injections between January 2002 and December 2008. There were 28 men (43.1%) and 37 women (56.9%). A total of 65 injections were performed, with a mean time to follow-up of 4 years (range, 6 months to 8 years). Patients were followed through telephone questionnaires. A total of 38 of the original 65 patients responded to survey. Nine of the patients in their study reported sudden improvement after injection of the local anesthetic, confirming that the hamstring tendon was indeed the cause of their discomfort. No significant side effects or complications were reported by any of the patients undergoing injection. Furthermore, there was an excellent clinical response to corticosteroid injection, with 50% of patients reporting moderate-to-complete resolution of their symptoms for at least 1 month after the injection and 28.9% reporting complete and sustained resolution of symptoms post injection.

In a RCT, Cacchio et al.26 compared the efficacy of ESWT alone to a general conservative treatment protocol in 40 professional athletes divided into two groups of 20 subjects each. The general conservative treatment protocol consisted in the administration of NSAIDs (Ibuprofen 600mg twice daily) for the first week, physiotherapy and an exercise program for the hamstrings. The exercise program included hamstring stretching and eccentric and concentric strengthening exercises for hamstring muscles, performed 3 days a week for 3 weeks. The patients were evaluated at 1 week and at 3, 6 and 12 months after treatment. The primary outcome measures used were the VAS, the phase Nirschl rating scale (NPRS). Significant differences were found between the two groups in favor of the group treated with ESWT in all scores. In addition, 16 patients in the ESWT group came back to sport at the same preinjury level. By contrast, none of the patients in the control group were able to return to preinjury level at follow-up evaluations.

Two studies were reported about the conservative treatment of adductor tendinopathy; 1 RCT and 1 single blinded, prospective, randomized controlled trial. Holmich et al.27 evaluated the long-term effect of an exercise protocol, validated in a previous RCT conducted by the same Authors, in which was compared the effectiveness of supervised active training program (AT) to a general program without active training (PT) in the treatment of adductor-related groin pain in 69 athletes of whom 59 completed the study. The AT consisted in exercises focused in muscular strengthening, mainly eccentric, with special emphasis on the adductor muscles, as well as training muscular coordination to improve the postural stability of the pelvis, while PT in manual techniques (tran sverse friction massage), electrotherapy (laser and transcutaneous electrical nerve stimulation), and exercise therapy (stretching). Forty-seven athletes (80%) participated in the follow-up evaluation, in which the distribution of outcomes showed a significant difference in favor of the AT treatment, in terms of pain reduction and return to sport participation at preinjury level.

Weir et al.28 in a single-blind, prospective, RCT compared two groups of 54 patients with diagnosis of adductor tendinopathy; one group was treated with the same exercise protocol of Hölmich et al. 27 (ET, n=22), while the other group with a multi modal treatment (MMT, n=26). Multi-modal treatment program (MMT) consisted in using heat, Van Den Akker manual therapy method, stretching and returning to running program. Primary outcome was time to return to full sports participation. Secondary outcome measures were objective outcome score and the VAS score during sports activities. The athletes were assessed by a single experienced blinded physician at baseline, 6, 16 and 24 weeks after the start of treatment. There was no significant difference in the number of athletes able to return to sporting activities between the two treatment groups. The objective treatment outcome and pain scores during sporting activities did not differ between the two treatment groups. The athletes in the MMT group significantly return more quickly to sports than athletes in ET. This clinical trial showed that the MMT was safe and equally effective treatment for athletes as an ET program. However, the Authors argue that the efficacy is lower than the results obtained in other studies in which were proposed.

Three studies on the conservative treatment of iliopsoas tendinopathy have been included.

Philippon et al.29 proposed a rehabilitative protocol based on gluteus medius strengthening, observing that a concomitant weakness of the gluteus medius in many cases of iliopsoas tendon pathology is often present. EMG signals of the gluteus medius and iliopsoas muscles were recorded from 10 healthy participants. Exercises were placed into respective time phases based on average gluteus medius EMG amplitude, exercises involving hip rotation were avoided in phase I (phase I, initial 4 or 8 weeks; phase II, subsequent 4 weeks; Phase III, final 4 weeks). It was identified a continuum of gluteus medius muscle activation for 13 common hip rehabilitation exercises and evaluated concurrent iliopsoas activation. Based on these data a continuum of hip rehabilitation exercises was identified. Resisted knee extension terminal, resisted knee flexion, and double-leg bridges were identified as appropriate for phase I and resisted hip extension, hip rotations stool, and side-lying hip abduction with wall-sliding for phase II. Hip clam exercises with neutral hips may be used with caution in patients with hip flexor tendinopathies. Heel squeezes prone, side-lying hip abduction with internal hip rotation, and single-leg bridges were identified for phase III.

Garala and Prasad30 in a retrospective case-control study evaluated the efficacy of psoas tenotomy and image-guided steroid injections. Twenty-three patients were evaluated over a time of 49 months for surgery and 77 months for injection. Eight patients had a lasting response to injection and not required more interventions. Fifteen patients submitted to psoas tenotomy, using Ludloff approach, of which 10 patients reported pain relief after tenotomy, while 5 patients reported no change in pain. The average NAHS after surgery was 66.15% and 76.08% after injection. The Authors conclude that local corticosteroid injection can provide long-term relief. For patients with only temporary relief from injection, psoas tenotomy could represent a valid treatment with long-term efficacy. Furthermore, the Authors sustained that patients who had no pain relief after injection, did not receive any benefit from the surgery.

Ryan et al.31 retrospectively reviewed 27 patients with presumed iliopsoas tendinopathy treated by a single fluoroscopically-guided injection of a combination of 1 mL depo steroid (Kenalog-40) (40 mg/mL) z 1 mL of bupivacaine 0.25%, and 1 mL of a 2:1 mixture of Conray-43 and 0.25% bupivacaine or 1% lidocaine. The treatment was promptly effective in 19 patients, while 8 patients (30%) required a second injection at an average of 8.2 months after the first injection. One patient had a third injection 3 months after second injection. Six patients had an additional surgical procedure to address the underlying cause of the iliopsoas irritation. The Authors concluded that selective steroid and anesthetic injections of the iliopsoas bursa represent a safe and effective treatment.

A retrospective study32, involved 39 patients affected by calcific tendinopathies around the hip. Subjective hip pain at the first visit was measured with VAS. During the follow-up, the VAS pain score and duration of symptoms were recorded. Standardized pelvic anteroposterior and lateral radiographs were taken to determine the size, location, and shape of calcific deposits. Of 29 patients (30 hips), 23 (24 hips) were managed with non-operative treatment. Among 30 hips, calcium phosphate crystals were located within the tendon of the gluteus medius muscle in 15 patients, the reflected head of the rectus femoris muscle in 9 hips, the capsule in 3 hips, and the piriformis, iliopsoas, and direct head of the rectus femoris muscle in 1 hip. The VAS score decreased from a mean of 7.1 (range, 5–10) at the first visit to 0.8 (range, 0–4) at the final follow-up visit. Of 6 patients (6 hips) who were treated with interventions, 2 patients with severe pain (VAS score 9 or 10) underwent ultrasound-guided local anesthetic and steroid injection. Both patients reported complete symptom subsidence at 4 weeks after injection. Radiographic evaluation showed complete disappearance of the calcifications with no recurrence at the final follow-up. The remaining 4 patients who reported pain after 3 months of non-operative treatment were treated using arthroscopic surgery.

Six studies were included: 1 open-label randomized trial, 2 RCTs, 1 case-control study, 1 retrospective study and 1 multicentric double-blind RCT. Four of these studies evaluate the efficacy of local corticosteroid injections, two the efficacy of ESWT, one study compares home training with local injections of corticosteroids and with ESWT.

Brinks et al.33 in an open label randomized trial compared the effectiveness of corticosteroid injections to usual care treatment, consisting in analgesics as needed. The injection according to a standard procedure: i.e. to use 40 mg triamcinolone acetate combined with lidocaine 1 or 2% in a 5 ml syringe. A clinically relevant effect of corticosteroids has been shown in the assessment after six weeks; at 3 months follow-up, the effect was decreased; after 12 months no differences were evident between the groups. The same Authors had compared the efficacy of corticosteroids to analgesics as needed in a previous study (RCT), in which corticosteroids were more efficient to reduce pain at three and six months, while results were not statistical different at 1 year follow-up.

McEvoy et al.34 compared the effects of cortico steroid injections in the trochanteric bursa to injections in the subgluteus medius bursa, showing that injections directed into the greater trochanteric bursa result in greater pain reduction than subgluteus medius bursa injections in the short-term treatment of patients with GTPS. Furthermore, there was no association between pain reduction and the ultrasound findings of tendinopathy, bursitis, or enthesopathy, suggesting that sonographic findings may not be predictive of response to treatment with corticosteroid injections.

Nevertheless, Cohen et al.35 found no differences in injecting within the trochanteric bursa, using fluoroscopic guidance or through simple anatomical landmarks. This could be due in part that patients with GTPS often have no signs of inflammation at the trochanteric bursa, and pain may result from problems in the surrounding structures.

Furia et al.36 have shown that ESWT determined greater clinical effects, considering the changes in the VAS score, Harris Hip Score (HHS) and the Maudsley scale, than other forms of conservative therapies in patient affected by chronic forms of GTPS, until 12 months of follow-up (p<0.0001).

Recently, the same Authors37 enrolled 229 patients with refractory unilateral GTPS that were assigned sequentially to a home training program (n=76), a single local corticosteroid injection (25 mg prednisolone) (n=75), or a repetitive low-energy radial shock wave treatment (n=78). While in the first month of follow-up corticosteroids were more effective than other treatment modalities, ESWT and exercise home based therapy were revealed both more effective at 15 months follow-up.

Labrosse et al.38, in a prospective study, evaluated 54 patients with clinical and US diagnosis of gluteus medius tendinopathy. All patients were administered a ultrasound-guided injection of 30 mg of triamcinolone combined with 3 mL of 0.5% bupivacaine using an anterior oblique coronal plane. One month after treatment, 72% of the patients showed a clinically significant improvement in pain level, which was defined as a reduction in the VAS pain score of ≥30%. Seventy percent of patients was satisfied with the results of the intervention.

The management of tendinopathies is changing with the progression of the research and the growing evidences on this argument39. Currently, the treatment should include early functional treatments, rather than rest and immobilization21. Several therapeutic options are allowed: eccentric and concentric exercise, ESWT, therapeutic ultrasound, low level laser therapy (LLLT), hyperthermia, splinting-bracing and orthoses, deep transverse friction and topical glycerine40,41.

Although hip tendinopathies are recognized as common causes of pain and functional impairment in athletes and in general population, actually the evidences are still lacking, compared to other tendinopathies. In our knowledge, most of studies aimed to determine short-term pain relief, while the long-term management is often not investigated.

Particularly, corticosteroid injection seems to represent the most used therapy, whereas the mechanisms of efficacy and safety, especially in repeated use, remain unclear. The use of corticosteroid injection is well-described but the clinical application may be limited by short-term efficacy. Corticosteroid injection has been suggested to provide an analgesic effect related to its interaction with local neuropeptides and neurotransmitters42. Repeated use is associated with tendon rupture whether the event is not common43. Recurrence of pain following corticosteroid injection may reflect the failure of the intervention to address the underlying pathology and the associated central mechanisms, thought to be important co-drivers of longer-term tendon pain44. Furthermore, corticosteroids may cause down-regulation of fibroblastic production of collagen, hiding tendon capacity to respond appropriately to loading44.

In the last years, an increased number of studies has been accomplished on the role of PRP or hyaluronic acid in tendinopathies, due in part to the superiority to corticosteroid in the long-term management of different tendinopathies. Furthermore, the use of PRP may avoid tendon rupture risk, related to corticosteroid injection. PRP could provide several molecules capable of boosting healing mechanisms and counteracting degenerative processes in tendinopathic tendon, restoring tissue architecture and enhancing tenocyte viability. In the present review, initial evidences in favor of PRP injections have been found only in the management of hamstring tendinopathy23,24, while the efficacy of this treatment in the other hip tendinopathies is not investigated yet. However, the encouraging results obtained, may allow to an ulterior option prior to surgical intervention.

ESWT has been shown to be effective for different tendinopathies, even for proximal hamstring tendinopathy and GTPS in long-term follow-up45,46. ESWT has proven to have direct benefits on tendon healing process, promoting neoangiogenesis, especially on tendon-bone junction, and inducing the up-regulation of nitric oxide and several growth factors: Insulin-like Growth Factor 1 (IGF-I), Platelet-Derived Growth Factor (PDGF), Vascular Endothelial Growth Factor (VEGF), basic Fibroblast Growth Factor (b-FGF), and Transforming Growth Factor beta (TGF-beta) 47.

Treatment regimens for ESWT vary dependent upon energy density, frequency of shockwaves and number of sessions. The studies evaluating effectiveness of ESWT present many variables including wave type (focal or radial), intensity per shock wave, frequency of the shock waves, type of SW generator and the overall treatment protocol. However, in our review, all the studies included opted for radial ESWT, whether no comparison study was already been performed between wave types.

Eccentric exercises (EE) applied as a regular training program over months are generally considered the gold standard for managing tendinopathies, especially patellar and Achilles tendinopathies48. EE has been demonstrated to improve tendon structure and muscle strength49. Although the lack of a general consensus, it has been noted that EE reduces the tendency of tendon to degenerate by increasing collagen content and reducing neovascularization50. Whether EE has been showed to be effective, programs are not well established yet, neither for dose, velocity and number of contractions or for period of treatment51. Nevertheless, in our review the use of EE is restricted to studies on hamstring tendinopathies, while there are no evidences in other sites hip tendinopathies. However, in adductor tendinopathies a combined approach of concentric and eccentric strengthening, endurance and neuromuscular training may be efficient in athletes to resume sports at their preinjury level and that exercise therapy may represent the therapy with the highest level of evidence for the treatment of adductor-related groin pain.

Indeed, it could be argued that each tendinopathy requires an appropriate and specific management. This is currently not practicable and it is therefore necessary that future studies should be conducted targeted for each specific tendinopathy around the hip.

Iliopsoas tendon pathology may be associated with chronic pain following hip surgery and even if is uncommon after THA, it should be considered in the differential diagnosis of all patients who present with groin pain after THA31. However, studies performed are largely focused on the surgical treatment omitting the conservative aspects. Actually, evidences about conservative approach are limited to corticosteroid injections that are often effective and determine lasting in pain relief. Selective steroid and anesthetic injections of the iliopsoas bursa give adequate pain relief in the majority of patients and should be considered part of the nonoperative management before surgical release of the iliopsoas tendon or component revision31. The lack of response to treatment with corticosteroids may be predictive of a poor response to surgery31.

For proximal hamstring tendinopathy injections with PRP may have interesting implications23,24. In our review, it emerges that the shock waves26 and injection with corticosteroids25 are efficient, but new types of training and exercises should still be considered.

Gluteal tendinopathy is the most frequent cause of pain in the greater trochanter region13. In the literature the treatment with corticosteroids injections has been shown to be effective38, whether studies with a long follow-up are still missing.

Studies about GTPS were included, because in most cases this pathological condition is related to medius and minimus gluteus tendinopathies14. Conservative treatment is the gold standard for GTPS with over 90% success rate, whereas there is currently no evidence-based protocol for the management of GTPS21.

Corticosteroids are useful to relieve pain and reduce inflammation52, especially in the short term (within three months after the administration)44. Several studies have shown that in the long term other conservative treatments are much more effective, as ESWT is the one with greater effectiveness especially in the long period for GTPS53.

Conservative treatment is effective in the management of hip tendinopathies and may be considered the first-line approach for patients affected. However, there is lack of evidences about which therapy should be indicated on patients affected by hip tendinopathies for two main reasons. First, only in the last years the pathologies of soft tissue around the hip were accurately categorized. Secondly, the literature available is low-quality and exiguous in volume. Most of studies performed are limited to corticosteroid injections, which represent a valid treatment in short-term pain relief, while the long-term use may impair tendon architecture, until tendon rupture. Therefore, further studies about different local approaches, as PRP or hyaluronic acid injections, may be encouraged. Long-term relief may be achieved with exercise therapy, whereas the literature is still lacking about the correct type, dose, posology, intensity of exercise prescribed.