Abstract
Objectives
The purpose of this study was to assess the safety of ultrasound‐guided corticosteroid injections into the posterior tibial tendon sheath for posterior tibialis tendinopathy. Secondary outcomes include duration of pain relief, amount of pain relief, need for repeat injections and progression to surgery.
Methods
We retrospectively reviewed all patients in our electronic medical record who underwent a posterior tibial tendon sheath (PTTS) steroid injection between 2015 and 2020 for the diagnosis of posterior tibial tendon dysfunction and/or posterior tibialis tendon insufficiency, and/or ankle pain. Demographic information was obtained from the patient record in addition to MRI data, clinical response to injection based on follow‐up visits, number of total injections and progression to surgery. Thirty‐eight posterior tibial tendon sheath ultrasound‐guided injections were administered in 33 patients who met inclusion criteria during the 5‐year study period.
Results
Thirty‐three patients were included in the study with a total of 38 injections performed. Eighteen of 38 (47%) injections yielded good or better pain relief. Seven of 33 patients (21%) progressed to surgery. There were no reported complications with the 38 performed injections.
Conclusion
Ultrasound‐guided corticosteroid injection into the posterior tibial tendon sheath is a safe nonoperative treatment modality for progressive collapsing foot deformity. The efficacy of the injection appears highly variable with 47% of injections yielding ‘good’ or better clinical results. When evaluating body mass index (BMI), obese patients (BMI ≥30.0) were found to have a more sustained response to injection (P = 0.029) and more pain relief (P = 0.049) than non‐obese patients.
Keywords: complications, efficacy, posterior tibial tendon dysfunction, progressive collapsing foot deformity, ultrasound‐guided corticosteroid injection
Introduction
The posterior tibial tendon (PTT) is a strong inverter and plantarflexor of the foot as it courses posterior to the medial malleolus to insert broadly on the navicular tubercle with fibres extending plantarly to reinforce the talonavicular joint capsule and distally to the first, second and third metatarsal bases. 1 The PTT is in part responsible for maintaining the arch of the foot. Similar to the peroneal and Achilles tendons, the PTT is susceptible to tendinopathies, which may eventually progress to tendon dysfunction and alteration of foot alignment and walking mechanics. 2
Although the exact aetiology of progressive collapsing foot deformity (PCFD) may be unknown, microtrauma with repetitive loading of the tendon in conjunction with the anatomic course of the tendon can lead to degenerative processes and dysfunction. 3 As the PTT courses posterior to the medial malleolus, it experiences increased tension at this site in addition to relative hypovascularity. 4 , 5
Historically, the treatment of posterior tibial tenosynovitis along with other tendinopathies has included physical therapy, 6 orthotics, bracing and ultimately surgery. In general, cortisone injections have been avoided around tendons due to the reported ruptures of the Achilles tendon related to cortisone injections. 7 , 8 However, recently, Fram et al. 9 published a study evaluating the efficacy and safety of peroneal tendon injections under ultrasound guidance. In our practices, we have begun providing cortisone injections of the PTT when other nonoperative modalities have failed. To our knowledge, there have been no studies to date evaluating the safety and efficacy of ultrasound‐guided corticosteroid injections in the PTTS for the treatment of PCFD in the adult population. The purpose of our study was to assess the safety of ultrasound‐guided corticosteroid injections into the posterior tibial tendon sheath for posterior tibialis tendinopathy. Secondary outcomes include the need for repeat injections, clinical response to injections and progression to surgery. We hypothesise that ultrasound‐guided posterior tibial tendon sheath injections are both safe and effective as a treatment for PCFD.
Materials and methods
This study was a retrospective review of patients treated at an academic institution with two board‐certified foot and ankle surgeons in addition to two board‐certified primary care sports medicine physicians who performed all ultrasound‐guided corticosteroid injections.
Prior to beginning the investigation, approval was obtained for the study from the University of Connecticut Health Center's Institutional Review Board. This chart review is secondary research for which consent is not required. This determination is made on the basis that the research only involves the collection and analysis of identifiable health information that was previously collected for the purpose of healthcare operations. The study was performed in its entirety in accordance with the ethical standards set by the Declaration of Helsinki.
Patients for inclusion in the study were identified based on billing codes (PTT injection—CPT 20550). Inclusion criteria consisted of adult patients (18 years old and older) who received a posterior tibial tendon injection for the diagnosis of posterior tibial tendon dysfunction (PTTD) and/or posterior tibialis tendon insufficiency, and/or ankle pain (prior to the change in nomenclature to PCFD). Injections were performed under ultrasound guidance by one of the two board‐certified sports medicine physicians and between 2015 and 2020. Patients who had prior foot and ankle surgery were included. Patients who had received other injections (tibiotalar, peroneal tendon sheath and midfoot) were included as long as they also received a posterior tibial tendon sheath injection under ultrasound guidance.
Patient chart review was conducted for patients who met the inclusion criteria, and baseline demographics, body mass index (BMI), durations of symptoms, smoking status, presence of diabetes, prior non‐steroidal anti‐inflammatory drugs (NSAIDs) treatment, presence of workers compensation injury, foot alignment based on clinical and radiographic analysis, MRI findings of tendon condition (if available), prior foot and ankle surgery, concomitant tendinopathies were recorded. Collected outcome measures included the following: duration of relief, amount of relief, number of injections, any adverse complications from injection and progression to surgery. Phone calls were used to supplement data that were not recorded in the patients’ medical record for seven patients.
Data were analysed using Microsoft Excel (© 2019 Microsoft Corporation) and Stata (© StatCorp 2021). Fisher's exact test of independence was used to determine the statistical significance of nominal variables.
Description of procedure
Injection technique was performed with the patient in a supine position with the leg in external rotation (Figure 1). The patient's area of maximum tenderness along the tendon was identified. Diagnostic evaluation of the tendon was then performed from the myotendinous junction distal to the tendon insertion in both cross‐sectional and longitudinal images of the tendon obtained (Figure 2). A high‐frequency linear probe was used for the diagnostic evaluation and injection. The location of the injection site along the tendon was determined based on the patient's symptoms and/or pathology by ultrasound mainly evidenced by tenosynovitis. Both anterior‐to‐posterior and posterior‐to‐anterior approaches were utilised in the study population. The tendon was visualised in cross‐section using the in‐plane needle approach to avoid the neurovascular bundle.
Figure 1.
Set‐up and technique of posterior tibial tendon sheath ultrasound‐guided steroid injection. Ultrasound‐guided posterior tibialis tendon injection set‐up. The patient is placed in a supine position with the leg in external rotation. The patient's area of maximum tenderness along the tendon is identified. Diagnostic evaluation of the tendon is then performed from the myotendinous junction distal to the tendon insertion in both cross‐sectional and longitudinal images of the tendon obtained. A high‐frequency linear probe is used for the diagnostic evaluation and injection. The location of the injection along the tendon is determined based on the patient's symptoms and/or pathology by ultrasound mainly evidenced by tenosynovitis. An anterior‐to‐posterior or posterior‐to‐anterior approach can be utilised. The tendon is visualised in cross‐section using the in‐plane needle approach to avoid injury to the neurovascular bundle. The bony anatomy of the medial malleolus may require a posterior‐to‐anterior approach.
Figure 2.
In‐plane image of ultrasound‐guided injection into the posterior tibial (PT) tendon sheath with neurovascular (NV) bundle imaged. The posterior tibial tendon is visualised in the retromalleolar region using a high‐frequency linear probe. The tendon is evaluated for signs of tenosynovitis and/or tearing. The flexor digitorum longus tendon, flexus hallucis longus tendon and local neurovascular structures are also identified. Using an in‐plane needle approach visualising the tendon in a cross‐section, a 25‐g 1.5‐inch needle is directed into the tendon sheath superficial to the above‐mentioned structures. Once in the tendon sheath, 1 ml of corticosteroid (depomedrol or betamethasone) mixed with 1–3 ml of 1% lidocaine is injected.
Results
We identified 39 posterior tibial tendon sheath ultrasound‐guided injections in 34 patients administered over a 5‐year period from October 2015 through June 2020. One patient was excluded from the study as he only had one procedural visit documented with no pre‐injection or postinjection visits or data points. This yielded a total of 38 injections in 33 patients to be included in the study (Table 1). Twenty‐two patients were female (66.7%), and 11 patients were male (33.3%). The average age was 51.3 (range from 19 to 78) years old. The average BMI was 29.9 (ranged from 18.9 to 45.5). Five (15.2%) patients were active smokers at the time of the injection, five (15.2%) were previous smokers and 23 (69.7%) had no smoking history. There were no patients with a diagnosis of diabetes in the study. None of the patients in the study received an injection due to a worker's compensation injury. Seventeen patients (51.5%) had a pre‐injection MRI. Eleven patients (33.3%) had concomitant tendinopathy of either peroneal tendons or Achilles tendon. Of the 33 patients included in the study, two patients (6.1%) had three PTT injections and one patient (3%) had two injections. Eighteen of 33 (54.5%) patients had ‘good’ or better results with the posterior tibial tendon sheath injection. Seven patients (21.2%) progressed to need surgical intervention after their injection. Four of these surgeries were either PTT repairs, debridement and/or reconstruction. Additionally, one patient went on to have a flat‐foot reconstruction with flexor digitorum longus transfer, gastrocnemius recession, calcaneal and cotton osteotomy and spring ligament repair. One patient underwent removal of irritating hardware from the medial malleolus, and one patient underwent a triple arthrodesis with resection of a calcaneal navicular coalition. There were no reported or apparent complications in all 38 injections.
Table 1.
Patient demographics with total of 33 patients included after criteria with a total of 38 injections
| Demographics | ||
|---|---|---|
| Patient characteristics | Injections (n) | Percentage |
| Total | 38 | 100.0% |
| Positive MRI | 17 | 44.7% |
| Clinical concomitant tendinopathy | 13 | 34.2% |
| Good or better response | 18 | 47.4% |
| Progressed to surgery | 7 a | 21.2% |
| Concomitant NSAID use | 23 | 60.5% |
| Current smoker | 5 | 13.2% |
| Smoking history | 6 | 15.8% |
| Obese (BMI ≥30.0) | 17 | 44.7% |
| Multiple injections (2 or more) | 5 | 13.2% |
| Worker's compensation | 0 | 0.0% |
| Complications | 0 | 0.0% |
BMI, body mass index; MRI, Magnetic resonance imaging; NSAID, Non‐steroidal anti‐inflammatory drugs.
Indicates number of patients, not injection encounters.
In subgroup analysis, there was no statistically significant difference (P ≤ 0.05) when comparing the length of pre‐injection symptoms to postinjection amount or duration of relief. There was a trend towards significance in patients who had a pre‐injection MRI positive for PTT pathology (17) with moderate or better pain relief following injection compared with patients who had a negative MRI or no pre‐injection MRI (P = 0.068). When evaluating BMI, obese patients (BMI ≥30.0) were found to have a more sustained response to injection (P = 0.029; Table 2A) and more pain relief (P = 0.049; Table 2B) than nonobese patients. No statistical correlation was found in relation to smoking status or NSAID usage with amount or duration of relief following injection.
Table 2A.
Comparison of obese and nonobese patients to duration of relief following injection
| BMI | Duration of relief | |||
|---|---|---|---|---|
| <2 weeks (%) | 2–6 weeks | >6 weeks | P | |
| Nonobese (BMI < 30.0) | 10 (62.5) | 6 (37.5) | 0 (0) | 0.029 |
| Obese (BMI ≥ 30.0) | 5 (31.25) | 6 (37.5) | 5 (31.25) | |
BMI, body mass index.
P value of 0.029 signifying statistical significance.
Table 2B.
Comparison of obese and nonobese patients to amount of relief following injection
| BMI | Amount of relief | |||
|---|---|---|---|---|
| No significant (%) | Moderate (%) | Near complete (%) | P | |
| Nonobese (BMI < 30.0) | 9 (56.25) | 3 (18.75) | 4 (25) | 0.049 |
| Obese (BMI ≥ 30.0) | 4 (25) | 1 (6.25) | 11 (68.75) | |
BMI, body mass index.
P value of 0.049 signifying statistical significance.
Discussion
To our knowledge, this is the largest study in the adult population evaluating the safety and efficacy of ultrasound‐guided corticosteroid injections into the posterior tibial tendon sheath. In our study, there were no complications reported.
A recent study by Fram et al. 9 investigating the efficacy and complication rate of ultrasound‐guided corticosteroid injections into the peroneal tendon sheath corroborates findings similar to our study.
Previous studies have shown much‐increased accuracy with ultrasound‐guided injections versus palpation‐guided corticosteroid injections. Muir 10 showed 100% accuracy with ultrasound‐guided steroid injections in the peroneal tendon sheath contrasted with only 60% accuracy with palpation‐guided technique in a cadaver study. At our institution, all foot and ankle tendon sheath injections are performed by sports medicine‐trained physicians using ultrasound guidance. Based on our data and Muir's study, 10 we recommend using ultrasound guidance for all foot and ankle tendon sheath injections due to increased accuracy and potential decrease in risk of intratendinous injection.
The amount of relief following the PTTS injection was quite variable in our study. This could be due to several reasons. Frequently, patients presented with concomitant tendinopathies. Even if improvement was seen in PTT pain and dysfunction, concomitant pathology could still lead to subjective complaints of pain in the foot and ankle. Occasionally, injections were performed for both therapeutic and diagnostic decision‐making. Just over half of the patients in our study had a pre‐injection MRI. The other 16 patients' diagnoses were made clinically without MRI demonstrating PTT tendinopathy. There was a trend towards significance in our study showing more efficacious injections when there was a pre‐injection MRI positive for PTT pathology (P = 0.068). Certainly, an ineffective PTTS injection can still yield clinically beneficial information when trying to elicit the aetiology of medial hindfoot pain.
Just over half (17) of the patients in our study had a pre‐injection MRI. Those that did have an MRI showing PTT pathology trended towards having more relief from an injection, though not statistically significant (P = 0.068). Previous studies have also shown that MRI findings for PTT pathology may not be as sensitive as ultrasound‐guided injections. Cooper et al. 11 compared local anaesthetic injection into the PTTS versus MRI in diagnosing posterior tibial tenosynovitis and found that local anaesthetic injection into the PTTS was a more sensitive test for the diagnosis of posterior tibial tenosynovitis. We do not believe that obtaining an MRI of the ankle is a necessary prerequisite before considering an ultrasound‐guided corticosteroid injection into the PTTS.
In our study, a steroid injection was portended to be more efficacious in obese patients than in nonobese patients. Nonoperative treatment for PTTD has been shown to be more effective in obese patients (BMI ≥30.0). O'Connor et al. 12 showed that obesity was a positive predictor towards successful nonoperative treatment for PTTD. This could be due to the relative inactivity of obese patients compared with nonobese patients, though further studies are needed to improve our understanding of this correlation.
This study does have several limitations. Due to the relative infrequency of PTTS steroid injections and thus the low number of patients in our study over a 5‐year period, the ability to detect complications in subsets of our patient population is not adequate. Only three patients in our study had more than one injection. Therefore, this study cannot address whether multiple steroid injections into the PTTS lead to an increased risk of tendon rupture. It is also a retrospective study and as such is limited based on the accuracy and amount of information that can be extracted from the medical record. Additional data were supplementally obtained through phone calls to patients. We had a relatively small sample size, which limited our ability to predict who would benefit from a PTTS injection and who would not based on demographics and other patient‐specific factors. Other than obesity being a positive predictor of injection success, no other patient demographics were shown to correlate with an efficacious injection. The patients in this study were all treated at an academic institution whose predominant payer population is state insured. These results may not necessarily translate to a private practice payer base. All injections were performed by two providers. The injections themselves were not standardised prior to beginning this study. There is some variety in the amount of medications (1–3 ml of 1% lidocaine was utilised) and the specific technique (anterior‐to‐posterior vs. posterior‐to‐anterior needle placement based on patients’ anatomy and location of injection) used by the two providers who performed the injections. Additionally, there were no validated patient‐reported outcome measures recorded with each office visit. This study could be improved by collecting prospective data with validated patient‐reported outcome measures.
In conclusion, our series of 38 PTTS ultrasound‐guided corticosteroid injections showed no complications. We found the efficacy of injections to be around 47% with 21.2% of patients progressing to surgery. Based on our data, we believe PTTS ultrasound‐guided corticosteroid injections to be a safe treatment option to alleviate pain in PCFD. Further research is needed to determine which patient‐specific factors portend to a successful injection and which patients will likely progress to surgery.
Author Contributions
Mark Spencer: Conceptualization (equal); data curation (equal); investigation (equal); writing – original draft (equal); writing – review and editing (equal). Matthew Hall: Data curation (equal); investigation (equal); methodology (equal). Allison Schafer: Data curation (equal); investigation (equal); methodology (equal). Lauren E. Geaney: Conceptualization (equal); formal analysis (equal); investigation (equal); methodology (equal); project administration (equal); supervision (equal); writing – review and editing (equal).
Authorship statement
All authors were vitally important in the completion of this study.
Conflict of Interest
There were no conflicts of interests for the authors related to this study.
Funding
This study received no external or internal funding.
Ethical Approval
Prior to beginning the investigation, approval was obtained for the study from the University of Connecticut Health Center Institutional Review Board.
Acknowledgement
The authors would like to thank Mark Cote for his contribution to statistical analysis.
This retrospective review analyses the efficacy and complication rate of ultrasound‐guided corticosteroid injections into the posterior tibial tendon sheath in the adult population. Both patient clinical results and ultrasound‐guided injection techniques and imaging are included in this manuscript. To our knowledge, these clinical results have not well been published in the literature on the adult population.
References
- 1. Guelfi M, Pantalone A, Mirapeix RM, Vanni D, Usuelli FG, Guelfi M, et al. Anatomy, pathophysiology and classification of posterior tibial tendon dysfunction. Eur Rev Med Pharmacol Sci 2017; 21(1): 13–9. [PubMed] [Google Scholar]
- 2. Watanabe K, Kitaoka HB, Fujii T, Crevoisier X, Berglund LJ, Zhao KD, et al. Posterior tibial tendon dysfunction and flatfoot: analysis with simulated walking. Gait Posture 2013; 37(2): 264–8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3. Henry JK, Shakked R, Ellis SJ. Adult‐acquired flatfoot deformity. Foot Ankle Int 2019; 41(1): 1–17. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4. Petersen W, Hohmann G, Stein V, Tillmann B. The blood supply of the posterior tibial tendon. J Bone Joint Surg Br 2002; 84(1): 141–4. [DOI] [PubMed] [Google Scholar]
- 5. Frey C, Shereff M, Greenidge N. Vascularity of the posterior tibial tendon. JBJS 1990; 72(6): 884–8. [PubMed] [Google Scholar]
- 6. Kulig K, Reischl SF, Pomrantz AB, Burnfield JM, Mais‐Requejo S, Thordarson DB, et al. Nonsurgical management of posterior tibial tendon dysfunction with orthoses and resistive exercise: a randomized controlled trial. Phys Ther 2009; 89(1): 26–37. [DOI] [PubMed] [Google Scholar]
- 7. Kleinman M, Gross AE. Achilles tendon rupture following steroid injections. Report of three cases. JBJS 1983; 65(9): 1345–7. [PubMed] [Google Scholar]
- 8. Newnham DM, Douglas JG, Legge LS, Friend JA. Achilles tendon rupture: an underrated complication of corticosteroid treatment. Thorax 1991; 46: 853–4. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9. Fram BR, Rogero R, Fuchs D, Shakked RJ, Raikin SM, Pedowitz DI. Clinical outcomes and complications of peroneal tendon sheath ultrasound‐guided cortisone injections. Foot Ank Int 2019; 40(8): 888–94. [DOI] [PubMed] [Google Scholar]
- 10. Muir JJ, Curtiss HM, Hollman J, Smith J, Finnoff JT. The accuracy of ultrasound‐guided and palpation‐guided pero‐ neal tendon sheath injections. Am J Phys Med Rehabil 2011; 90(7): 564–71. [DOI] [PubMed] [Google Scholar]
- 11. Cooper AJ, Mizel MS, Patel PD, Steinmetz ND, Clifford PD. Comparison of MRI and local anesthetic tendon sheath injection in the diagnosis of posterior tibial tendon tenosynovitis. Foot Ankle Int 2007; 28(11): 1124–7. [DOI] [PubMed] [Google Scholar]
- 12. O'Connor K, Baumhauer J, Houck JR. Patient factors in the selection of operative versus nonoperative treatment for posterior tibial tendon dysfunction. Foot Ankle Int 2010; 31(3): 197–202. [DOI] [PubMed] [Google Scholar]