Non-operative Treatment Options for Osteoarthritis in the Hip

Abstract

With the increased disability associated with osteoarthritis (OA) progression, and the significant socioeconomic burden of joint replacement surgeries, there is a need for more reliable conservative treatments for patients presenting with hip OA. Most studies of OA treatments involve the knee. We conducted a literature search and reviewed non-operative hip OA treatment recommendations by the Osteoarthritis Research Society International, the American College of Rheumatology, American Academy of Orthopedic Surgeons, and European Alliance of Associations for Rheumatology, as well as Cochrane Reviews. Non-steroidal anti-inflammatory drugs and corticosteroid injections are the most supported and recommended options for hip OA; other medications with potential benefits for short-term pain relief include acetaminophen and tramadol. Most societies recommend against the use of glucosamine, typical opioids, and viscosupplementation injections. Platelet-rich plasma has potential benefits, but evidence of its effectiveness is incomplete. Further research is needed to better inform and guide clinicians who create treatment plans for patients with symptomatic hip OA.

Introduction

Osteoarthritis (OA) is a degenerative joint disease prevalent in approximately 22.7% of adults in a globally aging and increasingly obese population [3,17]. Close to 30% of this population is affected by OA in the knee and approximately 10% is affected by symptomatic OA in the hip [34,36]. In addition to being a leading cause of pain, OA has both social and economic costs, thus efficient and effective management is crucial [32,33,62]. By 2030, the number of adults affected by hip OA or other musculoskeletal joint complaints is projected to reach 41.1 million, nearly double the amount reported in 2005 [52]. An expected increase in the demand for joint replacement surgeries [52] indicates a need for more reliable conservative treatment options for hip OA. Prior to surgical intervention, non-operative care serves as the first line of treatment. Activity modification, physical therapy (PT), medications, and injectables are common methods of non-invasive treatment options for patients with symptomatic hip OA.

As a leading cause of global disability [17], OA calls for several effective treatment options to minimize pain and slow progression. Non-steroidal anti-inflammatory drugs (NSAIDs) are the most supported non-operative care options for hip OA. Non-steroidal anti-inflammatory drugs are a first-line therapy that help to reduce inflammation and thus minimize pain [23]. If NSAIDs fail to produce effects, injectables are often the next line of treatment. Most literature on injectables is based on disorders of the knee; very few high-quality studies exist that support the efficacy of injectable use in the hip. For this review, we compiled research on current non-operative treatment options for hip OA. Specifically, we will focus on recommendations for medication and injectables, and we will expose gaps where future research is needed. We conducted a literature search using search terms of “hip osteoarthritis,” “osteoarthritis of the hip,” “hip OA,” and “arthritis.” In addition, we reviewed recommendations for the diagnosis and non-operative treatment of hip OA by the Osteoarthritis Research Society International (OARSI), the American College of Rheumatology (ACR), American Academy of Orthopedic Surgeons (AAOS), and European Alliance of Associations for Rheumatology (EULAR), as well as Cochrane Reviews.

Medications

With continued advancements in imaging, pre-arthritic hip surgery, and implant survival, treatment of the hip has evolved to allow for more aggressive non-operative interventions prior to the onset of severe arthritis. NSAIDs are one of the most widely prescribed and studied medications for hip OA [8,10,19,28,29,37,55,78]. NSAIDs are analgesics that help to reduce inflammation [23]. They can be consumed orally or applied topically and are believed to have an analgesic (pain-reducing) as well as antipyretic (fever-reducing) effect [23]. Although they are effective in an intermittent short-term dosage [19], these drugs pose risks to patients when used for longer durations. They are associated with both gastrointestinal and cardiovascular side effects and can be supplemented with a prostaglandin analog, proton pump inhibitor, or replaced with a Cox-2-specific inhibitor to minimize side effects [23,36,61]. NSAIDs demonstrate improvements in both pain and function in patients with OA in the knee or hip [8,10,19,28,37,55,69,78]. Of the many NSAIDs available, celecoxib, etoricoxib, rofecoxib, and diclofenac all suggest potentially promising results in the hip, with diclofenac at a dose of 150 mg/d being superior to ibuprofen, naproxen, and celecoxib [55]. NSAIDs continue to be the most supported and recommended form of non-operative treatment for OA [1,2,5,26,39,55,69]. However, while articles supporting their use in the hip have been published, most of the literature has been focused on their effects in the knee [19].

In addition to NSAIDs, acetaminophen (paracetamol), tramadol, glucosamine or chondroitin, and typical opioids are alternative medications prescribed for complaints of hip pain. Like NSAIDs, acetaminophen has both analgesic and antipyretic effects. Acetaminophen does not contain anti-inflammatory effects and is a commonly purchased over-the-counter medication [16]. The current best understanding for the mechanism of action for acetaminophen is its role in dampening the cyclooxygenase (COX) pathways and inhibiting the synthesis of prostaglandins [9,27,30]. Similarly, tramadol is an atypical opioid analgesic that is sometimes used in combination with acetaminophen for treatment of hip OA [68]. As an atypical opioid, tramadol has a lower affinity for the μ-opioid receptor and thus has less severe adverse effects than the typical opioids [31]. Tramadol consists of (+) and (−) enantiomers that inhibit serotonin and norepinephrine reuptake, respectively. Such an effect interferes with the pain transduction pathway in the central nervous system, resulting in an analgesic effect [31,47,54]. There is minimal support for the use of acetaminophen or tramadol in treating hip OA, with some studies demonstrating little to no significant difference in pain and physical function when compared with control groups [19,68,69]. In their most recent guidelines, OARSI recommended against acetaminophen [5], AAOS deemed research inconclusive [1], and ACR conditionally recommended it for short-term relief [39] (Table 1).

Table 1.

Summary of hip OA treatment guidelines from medical societies.

	AAOS	ACR	EULAR	OARSI	Cochrane
Medications
NSAIDs	Yes [2,3]	Yes [39]	Yes [26]	Conditional Yes [5]	Conditional Yes [55,69]
Acetaminophen	Yes [3]	Conditional Yes [39]		Conditional No [5]	Conditional Yes a [69]
Tramadol	Yes [3]	Conditional Yes [39]			Neutral [68]
Glucosamine	No [3]	No [39]			Conditional Yes [64]
Typical opioids		Conditional No [39]		No [5]	No [18]
Injectables
Corticosteroids	Yes [2,3]	Yes [39]		None b [5]
Viscosupplementation	No [3]	No [39]		None b [5]	None b [7]
PRP		No [39]

Summarized up-to-date guidelines from the AAOS, ACR, EULAR, OARSI societies, and Cochrane Reviews database. “Yes” indicates strong recommendation for treatment use; “Conditional Yes” indicates moderate recommendation or limited evidence for use; “Conditional No” indicates moderate recommendation against or limited evidence against use; “No” indicates strong evidence and recommendation against use. “Neutral” indicates the treatment was discussed but neither suggested for nor against. When the society guidelines or Cochrane database did not address a particular non-operative treatment option, the corresponding box in the table was left blank. Table recommendations under Cochrane Reviews represent a summary of article findings from the database, rather than formal guidelines from a medical society.

OA osteoarthritis, AAOS American Academy of Orthopedic Surgeons, ACR American College of Rheumatology, EULAR European Alliance of Associations for Rheumatology, OARSI Osteoarthritis Research Society International, NSAIDs non-steroidal anti-inflammatory drugs, PRP platelet-rich plasma.

^aIndicates moderate recommendation but not as effective as NSAIDs.

^bIndicates recommendation for use in the knee, but no recommendation for use in the hip.

Glucosamine and chondroitin are nutritional supplements containing the amino acid components of cartilage and synovial fluid. They are proposed to maintain and slow or prevent cartilage degradation. However, sufficient evidence to support their use in treatment of hip OA is lacking [64]. Most studies of chondroitin have been done in the knee [64]. When consumed alone or in combination with glucosamine, chondroitin demonstrates slight improvements in OA-related knee pain when compared with control groups [64]. Studies with such findings, however, are of low quality, suggesting a need for additional research looking specifically at OA in both the knee and hip [64]. Typical opioids comprise another group of analgesic agents. With little support for their use, the high risk of adverse events—such as addiction, overdose, dampened functioning, and physiological dependence—overshadows any small benefits [18,21,74]. Thus, typical opioid use is often recommended against [5,18,39], and treatment with NSAIDs and other medications is preferred.

Injectables

As hip OA progresses and NSAIDs and other medications become less effective, stronger treatment options may be necessary. Still considered non-operative, injectables offer a targeted approach to treatment of hip OA. To increase hip joint injection accuracy and confirm needle placement without exposure to radiation, fluoroscopic or ultrasound guidance should be used [12]. In the absence of image guidance, intra-articular placement accuracy ranges from 67% to 88% [63]—a number that increases to 97% with ultrasound guidance [66]. While most studies of injections focus on the knee, this review will highlight hip-specific injection studies.

Corticosteroids are a class of steroid hormone released by the adrenal cortex. Corticosteroids include both glucocorticoids (anti-inflammatories and immunosuppressants) and mineralocorticoids (ionic balance regulators) [35]. The genomic and non-genomic pathways are the 2 most common mechanisms of action for glucocorticoids. In the genomic pathway, glucocorticoids bind to receptors and translocate to the nucleus where they can directly activate or suppress gene transcription and regulate expression. In the non-genomic pathway, biosynthesis of prostaglandins, cell proliferation and maturation, and transcription of proinflammatory cytokines are inhibited. Such an effect suppresses the inflammatory response. Corticosteroids may be inhaled, consumed orally, applied topically, or injected intravenously, intramuscularly, or intra-articularly [20]. Intra-articular corticosteroid injections are frequently used in the knee, due to ease of injection into a single joint. However, in the hip, injections must be done under guidance to ensure needle placement accuracy [66]. Corticosteroid injection into an arthritic hip has demonstrated short-term improvements in pain, function, and range of motion [4,14,25,43,44,46,56]. With these findings, society guidelines recommend corticosteroid injections as a viable non-operative treatment option for individuals with symptomatic hip OA [1,2,39] (Table 1). However, as many of the conducted hip studies were not randomized or anonymized [44], future research should determine the safety and efficacy of corticosteroid injection use. Interestingly, studies in the knee have shown steroid injections to have no greater effect than placebo after 3 months [13] and to be inferior to PT by the 1-year mark [48]. Thus, recommendations suggest a short-term benefit of corticosteroid injections in the knee, but there is insufficient data to specify duration of effect for injection into the hip [5].

In terms of risk, corticosteroid injections are correlated with subchondral fractures and osteonecrosis and may induce rapid progression of arthritis, increase the risk of infection, or have a deleterious effect on cartilage [40,48,79]. Locally, they may lead to fatty atrophy, pain exacerbation, or septic arthritis [50,51,73,76]. Despite possible adverse effects, ACR [39] and AAOS [1,2] both recommend the use of corticosteroid injection as a non-operative treatment for hip OA. Because most studies on corticosteroid use are concerned with the knee [5,13,79], further research is needed to confirm efficacy prior to dependence on corticosteroid injection as a non-operative treatment option for hip OA.

Viscosupplementation is an alternative injectable to intra-articular corticosteroids. During viscosupplementation, hyaluronic acid (HA), a glycosaminoglycan found in synovial fluid and various tissues [24,49], is injected into the affected joint in an attempt to reduce arthritic pain and swelling. Although some studies report positive outcomes following HA injection, other studies showed that HA was no more effective than a placebo or saline control [4,57]. One study found potential improvement, but this improvement was small and the study sample size was insufficient [56]. In studies on the knee, viscosupplementation was strongly associated with risk of serious adverse events [58], contributing to the absence of recommended use in society guidelines [1,39] (Table 1). The inconsistencies and lack of evidence on viscosupplementation in hip OA suggest a need for more studies to demonstrate efficacy.

Platelet-rich plasma (PRP) is the third injectable to consider; PRP is an orthobiologic, and treatment involves using one’s own filtered and concentrated blood components. Naturally occurring growth factors in the concentrate help to facilitate tissue healing in injected sites. PRP has an anti-inflammatory effect and achieves best results when prepared in leukocyte-poor formulations [42,72,77]. Compared with HA and corticosteroid injections, PRP intra-articular injections have been less studied and thus less widely used in the hip [22]. The literature suggests reductions in hip pain and improvements in function and mobility [59]. However, such outcomes are not superior to those achieved by HA [6], and similar positive results can be seen with a placebo [57]. Despite current clinical use, strong evidence for PRP and related injections is lacking, and more studies are needed to establish the use of orthobiologics for the treatment of hip OA.

Discussion

With medications and injectables readily available, it is important to consider when and with whom they should be used. Much of evidence on the efficacy of these non-invasive treatments is focused on the knee. Thus, more studies focusing on the hip are needed to reliably determine non-operative treatment options for patients presenting with hip OA. In addition to the treatments discussed, PT and exercise training can offer potential benefits to hip OA. These may extend one’s surgical timeline and better preserve a hip prior to the onset of severe arthritis. PT is a good supplement to NSAIDs due to its minimal risk of adverse events and its conservative approach to treating pain. PT exercises can be personalized to patients depending on hip morphology and individual need. Like injectables, there is a call for more randomized controlled trials with significant power and sufficient evidence to better understand the long-term treatment potential of PT [15,65,70].

In addition, when deciding whether to inject an arthritic hip, a better and more comprehensive assessment of OA is needed. Currently, we rely on the Tönnis and Kellgren-Lawrence grading systems to classify arthritis [67]. Tönnis classification consists of 3 degrees of degeneration. Grade 0 indicates no signs of OA, and grades 1 to 3 indicate increasing presence of OA, with grade 3 suggesting existence of large cysts, severe joint space narrowing, femoral head deformity, and avascular necrosis [41]. The Kellgren-Lawrence scale grades a joint from 0 to 4, with 0 suggesting no OA and grade 4 indicating severe OA [38]. The problem with these scales is that they look only at the relationship between the acetabulum and femoral head. They fail to account for potential comorbidities of age, gender, cam morphology, profunda, and/or dysplasia [71], leading to an incomplete judgment and classification of arthritic hips. Using a more comprehensive scale would allow for greater precision in the assessment of arthritis. It would provide more contexts for treatment effects on specific groups, helping to explain why some options may be effective in one population but ineffective in another.

An improvement in our grading systems becomes increasingly important when considering the role of hip morphology in the progression of hip OA. Looking at a cohort of total hip arthroplasty (THA) patients, Wyles et al [75] sought to understand the progression of OA based on morphological characteristics. Researchers demonstrated an increased progression of OA for patients with developmental dysplasia of the hip, compared with patients with femoroacetabular impingement or normal morphology. At the 10- and 20-year time points, the dysplastic hip patients had a higher probability of undergoing THA. Such data stresses the importance of more informed treatment decisions, taking into consideration potential comorbidities, and intervention timing and treatment type.

The risk of infection is another reason caution needs to be exercised when considering injections for hip OA. With our current grading system, a Tönnis score of 3 typically indicates a need for THA [11,80]. When THA is performed in patients who have received a steroid injection within 3 months, researchers have found an association with increased risk of periprosthetic joint infection. Such findings suggest that injected patients should delay THA for at least 3 months after the injection, prolonging the treatment process due to the unnecessary use of an injectable [45,53,60]. Thus, the decision to inject an unfit patient results from a lack of education and incomplete understanding of the risk of inappropriate injection. When providers follow the narrow guidelines of our current system, injectables may harm and delay treatment.

Potential adverse effects and the lack of research on hip OA, in combination with the unreliability of our current grading system, contribute to the lack of consensus on the use of injectables in patients complaining of disabling hip pain. In addition, we need to better educate providers on if and when to intervene with injectables. Due to risks of infection and the rapid degradation of dysplastic hips, we cannot simply inject any arthritic hip; we need to ensure that providers are aware of the consequences associated with injectables and other non-operative treatments.

In conclusion, among non-operative treatments of hip OA, NSAIDs and corticosteroid injections remain the most supported and recommended courses of action [1,2,5,26,39,55,69] (Table 1). However, only ACR [39] and AAOS [1,2] recommend the use of corticosteroids due to limited research on their efficacy in the hip. Although potentially promising results may ultimately support future use of PRP, strong evidence is lacking; more research must be done before PRP is considered a reliable treatment. Due to increased risk of infection and other adverse effects, hip injections must be performed with caution until better hip grading systems are available. Because hip OA is so prevalent globally, the lack of current literature and the flaws in our grading systems present significant obstacles. Further research is required to better inform and guide clinicians who create treatment plans for patients presenting with symptomatic hip OA.