Low-dose radiotherapy for greater trochanteric pain syndrome—a single-centre analysis

Strahlentherapie und Onkologie https://doi.org/10.1007/s00066-023-02107-4 ORIGINAL ARTICLE Low-dose radiotherapy for greater trochanteric pain syndrome—a single-centre analysis Michal Staruch1,2,3 · Silvia Gomez1 · Susanne Rogers1 · Istvan Takacs4 · Thomas Kern1 · Sabine Adler5 · Dieter Cadosch6 · Oliver Riesterer1 Received: 24 January 2023 / Accepted: 4 June 2023 © The Author(s) 2023 Abstract Purpose To determine predictive factors associated with a good response (GR) to and efficacy of low-dose radiotherapy (LDRT) in patients with greater trochanteric pain syndrome (GTPS). Methods Patients with GTPS were irradiated on a linear accelerator with 0.5–1.0 Gy per fraction to a total dose of 3.0–4.0 Gy per series. The endpoint was subjective good response (GR) to treatment 2 months after completion of the last LDRT series, defined as complete pain relief or marked improvement assessed using the von Pannewitz score. A positive response to steroid injection (SI) was defined as pain relief of at least 7 days. Patient and treatment-related characteristics were evaluated with respect to LDRT outcomes. Results Outcomes were assessed for 71 peritrochanteric spaces (PTSs; 65 patients, 48 females, with mean age of 63 [44–91] years). Prior SI had been given to 55 (77%) PTSs and 40 PTSs received two series of LDRT. Two months after completion of LDRT, GR was reported in 42 PTSs (59%). Two series of LDRT provided a significantly higher rate of GR than one series (72.5 vs. 42% PTSs, p = 0.015). Temporary pain relief after prior SI predicted GR to LDRT compared with PTSs which had not responded to SI (73 vs. 28% PTSs, p = 0.001). A regional structural abnormality, present in 34 PTSs (48%), was associated with a reduction of GR to LDRT (44 vs. 73% PTSs, p = 0.017). Conclusion LDRT is an effective treatment for GTPS. Administration of two LDRT series, prior response to SI, and absence of structural abnormalities may predict significantly better treatment outcomes. Keywords Radiotherapy · Trochanteric bursitis · Greater trochanteric pain syndrome · Low-dose radiation therapy · Benign disease Introduction  Michal Staruch 1 Center for Radiation Oncology KSA-KSB, Kantonsspital Aarau, 5001 Aarau, Switzerland 2 Clinical Trial Unit, Department of Clinical Research, University Hospital of Basel, University of Basel, 4031 Basel, Switzerland 3 University of Bern, Hochschulstrasse 6, 3012 Bern, Switzerland 4 Center for Radiation Oncology KSA-KSB, Kantonsspital Baden, 5404 Baden, Switzerland 5 Department of Rheumatology, Kantonsspital Aarau, 5001 Aarau, Switzerland 6 Department of Orthopaedic and Traumatology, Kantonsspital Aarau, 5001 Aarau, Switzerland Chronic pain and tenderness in the lateral aspect of the hip are relatively common clinical features, with a prevalence of up to 25% in the general population [1] and a preponderance in females (60%) [2], the latter likely due to female pelvic anatomy and tighter iliotibial bands [3, 4]. This clinical picture is commonly summarized as greater trochanteric pain syndrome (GTPS) and was formerly known as a trochanteric bursitis. For diagnosis of GTPS, physical examination remains the gold standard [4] and typically reveals a positive Trendelenburg test [5], reduced 30-s single-leg stance, and resistant external de-rotation tests as well as a positive FABERE (flexion, abduction, external rotation, extension) test [6]. Most frequent radiological findings include trochanteric bursitis and gluteal tendinopathy, with an incidence ranging from 4 to 46% and from 18 to 50%, respectively [7]. Notably, the co- K Strahlentherapie und Onkologie existence of the two aforementioned magnetic resonance imaging (MRI) findings [8] with other pathologies is not uncommon. In addition, due to the overlapping symptomatology of GTPS with, e.g., lumbar radiculopathy [9, 10], GTPS seems to be both underdiagnosed and misdiagnosed, potentially having social and economic consequences [11]. The aetiology of GTPS is still debated and a variety of conditions purportedly contribute to its pathogenesis. Although the exact pathogenetic mechanism remains to be elucidated, it is plausibly due to tears of gluteus medius and/or minimus tendons and friction between them, their bursae, the iliotibial fascia and the trochanter [12], all leading to disorganization of the collagen bundles. In addition, hypercellularity, increased proteoglycan synthesis and neovascularization are contributory [13, 14]. The most prevalent differential diagnoses encompass osteoarthritis of the hip joints, lumbar radiculopathy, rheumatoid arthritis, external coxa saltans or, less often and indirectly via altered biomechanics, discrepancy in leg length, pes planus, and genu varum or valgum [6]. Diverse treatment approaches are adopted for GTPS and include the use of anti-inflammatory analgesics and opiates, local injection of corticosteroids and local anaesthetics, physical therapy with infrared rays, shock waves, ultrasound, cryotherapy and thermotherapy [15, 16]. In patients who do not respond to the aforementioned conservative measures, low-dose radiotherapy (LDRT)—usually with six fractions (0.5–1.0 Gy per fraction)—is often the last conservative treatment modality to be tried for the persistent tendinitis. Its likely effectiveness has already been demonstrated in various conditions with active inflammation such as painful plantar fasciitis, achillodynia or painful elbow syndromes [17], albeit to a large part in retrospective analyses of large patient cohorts, thus establishing its place in clinical practice [11]. The predominant mechanisms by which LDRT exerts its biological effects include inhibition of mononuclear leucocyte adhesion, induction of apoptosis and the resultant blockade of various inflammatory pathways [18, 19]. As data regarding efficacy of LDRT in GTPS remain relatively scarce, we aimed to add to the evidence with our patient series. Defining the role of LDRT in modern management of GTPS may facilitate both decision-making before initiation of radiation treatment in patients suffering from refractory hip pain and provide a rationale for delaying surgical procedures [20]. K Methods Study design This present study was a single-centre retrospective analysis which sought to identify predictive factors associated with a good response (GR) to LDRT in patients with persistent GTPS. The study was reviewed and approved by the regional ethics committee (northwest and central Switzerland, approval no.; 2020-02932). Patients and treatment Patients irradiated between May 2015 and January 2021 twice a week on a linear accelerator with 0.5–1.0 Gy per fraction using opposing fields with 6-MV photons to a total dose of 3.0–4.0 Gy per series were included. SIs were administered by general practitioners and usually consisted of triamcinolone acetate (40–80 mg) combined with lidocaine or bupivacaine. Patients received up to four steroid injections (SIs), with the last injection at least (...truncated)