A Claims Based Natural History of the Post-Treatment Period after a Unilateral Ankle
Fracture



Robert B. Weinstein DPM1,Samantha J Beckley PhD2, Maha Karim BS3, Shaun K Stinton PhD2, Thomas P Branch MDb

1Ankle and Foot Centers of Georgia, 1819 Peachtree Street, Atlanta, GA, 30309, United States

2 ArthroResearch LLC, 441 Armour Place NE, Atlanta, GA, 30324, United States

3 Ermi LLC, 2872 Woodcock Blvd. Suite 100, Atlanta, GA, 30341, United States


Address for correspondence:

Samantha Beckley, 441 Armour Place NE, Atlanta, GA, 30324, USA

Phone: +1 404-579-1546

Email: s.beckley@arthroresearch.com.
Abstract: 250 words Objective: The aim of this paper was to determine a claims-based timeline of unilateral ankle fracture recovery including the effect of comorbidities and post-surgical complications on recovery. Methods: Healthcare claims data were analyzed to determine the costs and recovery timeline after unilateral ankle fracture treatment. Costs related to: 1) index surgery/treatment, ii) complication surgery, iii) revision surgery after ankle fracture (Salvage), iv) non-operative hospitalization, v) motion restoring surgery and vi) ankle-related outpatient surgery were reported. The effect of comorbidities was determined using data from patients with: diabetes, obesity, peripheral vascular disease, and cardiovascular disease. The effect of post-index surgical complications was determined using data from patients who were re-hospitalized (with or without additional surgery). Perioperative complications including joint fibrosis/contracture, infection, and pulmonary embolus were also reported. Results: Index surgery/treatment median cost was $5,163 ($994 to $12,444). Median length of post-treatment recovery (from index surgery/treatment to last physical therapy claim) was 88 days (36-492 days). A total of 38% of patients had a recovery time of over six months. The recovery period and cost for patients that required a complication surgery were over four times longer and added eight times the cost in comparison to patients not requiring any complication surgeries. Conclusion: Comorbidities and complications after ankle fracture lead to dramatically increased costs and recovery times. Knowing the timeline of recovery in the typical ankle fracture patient and in outlier patients can help manage recovery and determine appropriate interventions.
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2500 word limit for Orthopedics Introduction: Ankle fractures are very common injuries seen in medical practice with an incidence of 4.22/10,000 person-years (approximately 141,000/year in the United States) 1 . The injury and its sequelae can have a profound impact on patient mobility limiting work and play 2 . While most ankle fractures are limited to the fibula and can be managed postoperatively with early weightbearing, nearly one third involve both the tibia and fibula resulting in a period of non-weightbearing in a cast 3 . Prolonged immobilization can lead to ankle and/or achilles tendon contracture leading to a difficult post-treatment recovery 4 . Comorbidity such as peripheral vascular disease (PVD) can affect recovery through diminished blood supply leading to skin or wound issues and the need for additional surgery 5-7 . Reduced mobility can also be a setup for a deep venous thrombosis 4 . It is important to understand all potential risk factors associated with an ankle fracture and their accumulation during the post-treatment recovery period 8 . By defining this post-treatment “natural history” as a recovery timeline after an ankle fracture we can begin to design treatment processes that better manage their outcomes. Defining and understanding the typical recovery period following a treatment intervention is a crucial first step toward improving outcomes. While most studies focus on case series with a minimum two-year follow-up, the short-term recovery phase is often overlooked. This omission is significant, as a considerable portion of healthcare spending occurs during this early recovery period. Establishing a "Natural History" of the short-term recovery phase requires a much larger dataset than is typically available in standard case series. Such a dataset is essential to capture the full range of potential recovery pathways and outcomes comprehensively.
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The IBM MarketScan Database is a comprehensive resource for analyzing real-world healthcare utilization, costs, and outcomes. It includes de-identified claims data from over 250 employers and health plans, representing a large, insured population in the United States. The database provides longitudinal data enabling robust analyses of treatment patterns, economic burden, and clinical outcomes. Its extensive coverage and detailed information make it a valuable tool for health economics and outcomes research 9 . The aim of this study was to perform a claims-based timeline analysis of unilateral ankle fractures, tracking progress from the initial surgery/treatment to the final physical therapy session to establish a natural recovery timeline. An additional objective was to assess the impact of comorbidities and post-treatment complications on the overall recovery trajectory. Methods: Study Population This study leveraged healthcare claims data from the IBM MarketScan database (2015–2018), which encompasses detailed information on 11 million unique patients and over 1 billion claims. The analysis was retrospective and exempt from IRB review. Patients were included if they maintained continuous insurance coverage for at least two consecutive years. Ankle fracture patients were identified by CPT codes for ankle fractures (Addendum #1), while individuals with bilateral ankle fracture (either simultaneous or staged) were excluded to prevent bias in recovery duration and cost estimates. Both patients treated with open (surgical) and closed (casting) techniques were included in the analysis. The post-treatment period was defined as the time span
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from the index ankle fracture surgery or treatment to the final recorded HCPCS CPT charge for physical therapy (PT). To ensure the study focused on patients engaging in post-treatment rehabilitation, inclusion required at least one PT CPT charge (codes ≥97000 and <98000) within the recovery timeline. This approach yielded a dataset of 7,112 patients for evaluating recovery patterns and outcomes. Cost Analysis Costs associated with the index surgery/treatment represent all healthcare dollars spent during inpatient hospitalization or within eight days of the outpatient treatment. Subsequent procedures were grouped into categories: i) Complication-related surgery, ii) Ankle fracture revision and/or salvage to arthroplasty, iii) Non-operative hospitalization, and iv) Motion restoring surgery (MRS). Total Costs in each group represent all healthcare dollars spent which included the cited index treatment and any additional post-index treatment events. Therefore, these costs are a true representation of the event and the risk of related subsequent events. Standard CPT codes for post-treatment costs, such as PT (>=97000 & <98000), physician visits (>=99200 & <99300, plus injection CPT codes 20610/20611), and radiology, were also analyzed (see Addendum #1). Costs unrelated to ankle fracture were excluded from the analysis by absence of ankle-related ICD 9/10 codes on the HCPCS form. All reported costs reflect insurance-paid amounts. Comorbidities This study evaluated the impact of comorbidities on recovery timelines by analyzing specific patient subsets. Groups were identified based on the presence of diabetes (ICD-9/10 codes 25.0, E11.9), obesity (codes 278., E66., Z68.4), PVD (codes 440.:444., 785., I73.9), joint infections (codes 711., 996., M00., M01, M02), cardiovascular disease (CVD; codes 390.:459., I11, I20,
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I21, I25), and ankle contracture (codes 718.47, M24.57). For each subgroup, median costs and interquartile ranges (IQR) were calculated. Additionally, the incidence rates of infection (Addendum #6) and pulmonary embolism (Addendum #7) were analyzed. Index Surgery/Treatment All expenses related to the initial surgery or treatment were included, identified by the CaseID for inpatient surgery. For surgeries or treatments performed in outpatient settings where no CaseID was available, all costs incurred within an 8-day window were included in the total index costs to account for claims submitted over time. In cases where an ankle fracture procedure began in an outpatient setting but the patient was transferred to a hospital within eight days, these costs were included in the outpatient index surgery expenses. Patients undergoing inpatient surgery followed by a transfer to an inpatient rehabilitation facility were treated as having two distinct hospitalizations, with the rehabilitation stay classified as a nonoperative hospitalization. The distribution of open versus closed treatment of ankle fractures is in Table 5 with 56% receiving closed treatment. Additional Post-treatment Surgeries The effects of post-treatment complications on recovery were evaluated, with particular attention to rehospitalizations both with and without additional procedures. This included ankle fracture revisions (Addendum #2), MRS (Addendum #3), and surgeries addressing other complications (Addendum #4). Rehospitalizations were identified through a new CaseID associated with or occurring after the initial treatment. Perioperative complications, such as joint contracture (Addendum #5), infections (Addendum #6), and pulmonary embolism (Addendum #7), were also examined.
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Presentation of Recovery Pathway An uncomplicated recovery pathway would be a course in which the patient undergoes the initial treatment, is discharged, participates in PT, and achieves recovery within six months. It is well established that injuries or surgeries transition from acute to chronic after the six-month mark, and insurance providers limit temporary or short-term disability coverage to this timeframe. To illustrate the complexities of recovery, a multi-pathway chart (Figure 1) demonstrates the combined impact of various post-treatment events, with a particular focus on the increased risks associated with MRS decisions. Rather than depicting a specific timeline, the chart emphasizes the cumulative risk of successive complications during the recovery period. Data Analysis Data were analyzed using the R statistical programming language (version 4.3.3). Due to the large sample size, results are reported as medians along with the IQR, representing the 25th to 75th percentiles. Results: Study Group Demographics A total of 7,112 ankle fracture patients within the IBM Watson Database had a minimum of two years continuous coverage. The group was 60.6% female and 39.4% male. The median age was 44 years with a range from 1 to 62 years (IQR:20-54 years)(Figure 2). Height and weight data were not available. Index Surgery/Treatment Costs
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Of the 7,112 patients, 596 were treated as an inpatient only, 6397 were outpatient and 119 started as outpatient, but ended as inpatient. The median cost of the index surgery/treatment was $5,163 (IQR:$994-$12,444). The median inpatient surgery/treatment cost was $14,567 (IQR:$3,223-$27,390). The median cost of outpatient treatment was $4,683 (IQR:$893-$10,984). If the patient started as an outpatient but ended as an inpatient the median cost was $23,788 (IQR:$17,658-$31,921). Recovery Period The median length of post-treatment recovery (time between index surgery/treatment and last PT claim) for a unilateral ankle fracture was 88 days (IQR:36-492 days). Only 62% of patients completed their post-treatment period in six months with 38% of patients taking over six months to complete PT (Figure 3). Patients who completed their post-treatment course in less than six months, spent a median of 45 days in structured outpatient PT whereas patients who completed their post-treatment course in over six months, spent a median of 648 days in structured outpatient PT. The additional post-treatment costs incurred after six months for patients undergoing PT beyond that point were a median of $2,324 (IQR:$1,029 to $4,885). Complicating Events We examined whether a difference exists in the length of the post-treatment recovery period after four major events that may occur after a unilateral ankle fracture: 1) MRS, 2) Complication surgery related to the ankle fracture, 3) Revision surgery after ankle fracture and 4) Nonoperative Hospitalizations related to infection or pulmonary embolus in the post-treatment period. After MRS, such as a manipulation under anesthesia (MUA), arthroscopy for lysis of adhesions or synovectomy, the median number of days in structured PT and the costs of post-treatment care
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both nearly tripled (Table 1). The median recovery period and cost for patients that required a complication surgery after a unilateral ankle fracture were four times longer and added eight times the cost in comparison to patients that did not require any complication surgeries (Table 1). Patients with ankle revision surgery (salvage) took six times longer and cost 31 times those patients not requiring revision; however the risk of revision is quite low (Table 1). Nonoperative hospitalizations for pulmonary embolus and/or infection increased the post-treatment period nearly two times (191 days vs. 86 days) at a median cost of $30,025 per event (Table 1). The cumulative effect on medical care costs and recovery time as a result of multiple events in the post-treatment period can be seen in Figure 4 and Table 2. In particular, the decision to perform a MRS substantially impacted the risk of requiring a complication surgery, with patients undergoing MRS being 12 times more likely to need complication surgery compared to those without a MRS (47% vs. 4%). A single ankle fracture with no complications, no revisions and no MRS had a median post-index treatment cost of $2,322 (Figure 4). We found that 7% of single ankle fractures required a secondary surgery, including complication-, revision-, as well as motion restoring-surgeries (Figure 4). This median cost surged dramatically to $78,205 with a revision surgery (Table 1). Out of the 7,112 patients that were observed with a unilateral ankle fracture, 6,880 patients did not undergo a MRS. These patients had a median of 85 PT days and the median post-treatment cost was $2,443 (Table 1). The median cost for patients that hadMRS $19,698 (IQR:$11,477-$33,997) with a median of 357 PT days (Table 1). Ankle Joint Motion Loss
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The presence of either ankle or achilles tendon contracture at the time of index surgery/treatment or after the index surgery/treatment doubled the post-treatment cost compared to patients without contracture. The median recovery time for both patients who had a contracture pre-treatment and those that had a contracture post-treatment were significantly greater than in the subset of patients who did not develop a contracture (six times greater and four times greater, respectively, Table 3). Impact of Comorbidities on Recovery The effect of the presence of diabetes, obesity, PVD and CVD is shown in Table 4. The clinical impact of these conditions on recovery was small, however, there were a larger number of pulmonary embolism events present in patients with PVD and CVD in comparison to those without any comorbidities. Discussion: The primary finding from this study was the establishment of a benchmark for the post-treatment period following unilateral ankle fracture which can provide a framework to monitor and manage patient progress during the early recovery phase. The median post-treatment recovery time was 88 days, however 38% of patients required more than six months to complete their post-treatment care. High levels of delayed recovery were also reported previously in a study in which 72% of patients still suffered from ankle stiffness and 52% had not returned to pre-injury activity levels at one year after treatment 10 . These large variations in recovery timelines underscore the complexity of ankle fracture recovery.
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A second key finding was that major post-treatment events, including MRS, complication surgeries, revision surgeries, and non-operative hospitalizations had a considerable impact on both the length of recovery and associated healthcare costs following unilateral ankle fractures. MRS may include the need for achilles tendon lengthening, which can occur as a result of prolonged or improper immobilization during treatment. The need for MRS adds nearly one year to the recovery period and may also be related to the incidence of infection. One study showed that smoking, postoperative malreduction and hardware removal prior to fracture union were the most important factors predisposing to a permanent complication following an ankle fracture infection 11 . It has been reported that post-traumatic osteoarthritis occurs in 25% of all ankle fractures with a higher rate in fractures classified as Weber B+C+ 8 . In the current study, only 5 patients received salvage surgery at a rate of 0.07%. Previously, high complication rates (28-35%) and reoperation rates matching or exceeding the 7% reported in this study (7-13.6%) have been reported 12,13 . The third important finding in this study was that the diagnosis of an ankle contracture (M24.57 or M67.0) in the pre- or post-treatment period after a unilateral ankle fracture led to a considerable increase in costs and time to recover. The median cost and recovery time for patients who developed a joint contracture after surgery were significantly higher than for those who did not develop a contracture (Table 3). Certainly major wound complications after an ankle fracture have had a negative impact on motion recovery and are likely related to infection 2,7,14 . Based upon the results of this study, surgeons should be aware that preoperative motion loss related to joint contracture portends a markedly prolonged post-treatment recovery (88 vs 537 days).
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The fourth key finding in this study highlights the impact of comorbidities on the cost and recovery time following unilateral ankle fracture. We found that the presence of diabetes added 60 days to the recovery time of an ankle fracture and that there was an increase in post-treatment pulmonary emboli as opposed to infection in this group. Most studies suggest that infection should be the cause of delay in patients with diabetes 15,16 . Consistent with earlier literature, an increase in pulmonary embolism events was found in patients with PVD and CVD with only CVD showing a clinically significant increase in infection risk 16-18 . There are multiple limitations with a HCPCS claims-based analysis. There is the presence of standard coding inconsistencies, particularly since this study spans the change from ICD 9 to ICD 10 codes. In this study, the Post-treatment period definition assumes that the patient is finished with medical care after the last PT visit. Another limitation of this study was that the database claims did not include the cost of prescribed drugs which would add healthcare dollars to the total costs. Conclusion: The benchmark for recovery after ankle fracture surgery established in this study provides a standardized framework for tracking and managing patient progress during the early stages of recovery. This timeline is necessary for evaluating the effectiveness of any new treatment strategies designed to enhance recovery outcomes. The significant recovery delays of nearly 40% of patients taking over six months to recover highlight the need for improved post-treatment care protocols after ankle fracture. References
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1. Scheer RC, Newman JM, Zhou JJ, Oommen AJ, Naziri Q, Shah NV, Pascal SC, Penny GS, McKean JM, Tsai J, Uribe JA. Ankle Fracture Epidemiology in the United States: Patient-Related Trends and Mechanisms of Injury. J Foot Ankle Surg. 2020 May-Jun;59(3):479-483. doi: 10.1053/j.jfas.2019.09.016. PMID: 32354504. 2. Chen B, Ye Z, Wu J, Wang G, Yu T. The effect of early weight-bearing and later weight-bearing rehabilitation interventions on outcomes after ankle fracture surgery: A systematic review and meta-analysis of randomised controlled trials. J Foot Ankle Res. 2024 Jun;17(2):e12011. doi: 10.1002/jfa2.12011. PMID: 38635458; PMCID: PMC11080868. 3. Jain S, Haughton BA, Brew C. Intramedullary fixation of distal fibular fractures: a systematic review of clinical and functional outcomes. J Orthop Traumatol. 2014 Dec;15(4):245-54. doi: 10.1007/s10195-014-0320-0. Epub 2014 Oct 11. PMID: 25304004; PMCID: PMC4244552. 4. Spierings JF, Nijdam TMP, van der Heijden L, Schuijt HJ, Kokke MC, van der Velde D, Smeeing DPJ. Cast versus removable orthosis for the management of stable type B ankle fractures: a systematic review and meta-analysis. Eur J Trauma Emerg Surg. 2023 Oct;49(5):2085-2095. doi: 10.1007/s00068-022-02169-6. Epub 2022 Nov 16. PMID: 36383226; PMCID: PMC10520166. 5. Manchanda K, Nakonezny P, Sathy AK, Sanders DT, Starr AJ, Wukich DK. A systematic review of ankle fracture treatment modalities in diabetic patients. J Clin Orthop Trauma. 2020 Dec 13;16:7-15. doi: 10.1016/j.jcot.2020.12.013. Erratum in: J Clin Orthop Trauma. 2021 Aug 05;21:101558. doi: 10.1016/j.jcot.2021.101558. PMID: 33717936; PMCID: PMC7920114. 6. Martijn HA, Lambers KTA, Dahmen J, Stufkens SAS, Kerkhoffs GMMJ. High incidence of (osteo)chondral lesions in ankle fractures. Knee Surg Sports Traumatol Arthrosc. 2021 May;29(5):1523-1534. doi: 10.1007/s00167-020-06187-y. Epub 2020 Aug 6. PMID: 32761358; PMCID: PMC8038951. 7. Monestier L, Riva G, Coda Zabetta L, Surace MF. Outcomes after unstable fractures of the ankle: What’s new? A systematic review. Orthop Rev (Pavia). 2022 May 31;14(4):35688. doi: 10.52965/001c.35688. PMID: 35769653; PMCID: PMC9235440. 8. Swierstra BA, van Enst WA. The prognosis of ankle fractures: a systematic review. EFORT Open Rev. 2022 Oct 26;7(10):692-700. doi: 10.1530/EOR-22-0065. PMID: 36287098; PMCID: PMC9619393. 9. Butler, A.M., Nickel, K.B., Overman, R.A., Brookhart, M.A. (2021). IBM MarketScan Research Databases. In: Sturkenboom, M., Schink, T. (eds) Databases for Pharmacoepidemiological Research. Springer Series on Epidemiology and Public Health. Springer, Cham. https://doi.org/10.1007/978-3-030-51455-6_20 10. Ramadi A, Beaupre LA, Heinrichs L, Pedersen ME. Recovery and Return to Activity 1 Year After Ankle Fracture Managed With Open Reduction and Internal Fixation: A Prospective Longitudinal Cohort Study. Foot Ankle Orthop. 2022 Apr 19;7(2):24730114221091806. doi: 10.1177/24730114221091806. PMID: 35464787; PMCID: PMC9021494.
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11. Ovaska MT, Mäkinen TJ, Madanat R, Vahlberg T, Hirvensalo E, Lindahl J. Injury. 2013 Jul;44(7):1002-6. doi: 10.1016/j.injury.2013.02.027. Epub 2013 Apr 3. PMID: 23561581 12. Andrés-Peiró JV, Pujol O, Altayó-Carulla M, Castellanos-Alonso S, Reverté-Vinaixa MM, Teixidor-Serra J, Tomàs-Hernández J, Selga-Marsà J, García-Sánchez Y, Molero-García V, Joshi-Jubert N, Minguell-Monyart J. Predictors of first-year postoperative complications after fixation of low-energy ankle fractures: A single-center, retrospective cohort study of 663 consecutive fractures. Rev Esp Cir Ortop Traumatol. 2024 Jul-Aug;68(4):363-372. English, Spanish. doi: 10.1016/j.recot.2023.11.027. Epub 2023 Dec 1. PMID: 38043738. 13. Macera A, Carulli C, Sirleo L, Innocenti M. Postoperative Complications and Reoperation Rates Following Open Reduction and Internal Fixation of Ankle Fracture. Joints. 2018 May 21;6(2):110-115. doi: 10.1055/s-0038-1653949. PMID: 30051108; PMCID: PMC6059857. 14. Höiness P, Engebretsen L, Strömsöe K. The influence of perioperative soft tissue complications on the clinical outcome in surgically treated ankle fractures. Foot Ankle Int. 2001 Aug;22(8):642-8. doi: 10.1177/107110070102200805. PMID: 11527025. 15. Nash WJ, Hester T, Ha J. Current concepts and challenges in managing ankle fractures in the presence of diabetes: A systematic review of the literature. J Clin Orthop Trauma. 2021 Feb 3;17:44-53. doi: 10.1016/j.jcot.2021.01.016. PMID: 33717970; PMCID: PMC7919966. 16. Schepers T, De Vries MR, Van Lieshout EM, Van der Elst M. The timing of ankle fracture surgery and the effect on infectious complications; a case series and systematic review of the literature. Int Orthop. 2013 Mar;37(3):489-94. doi: 10.1007/s00264-012-1753-9. Epub 2013 Jan 4. PMID: 23288046; PMCID: PMC3580081. 17. Lorente A, Pelaz L, Palacios P, Benlloch M, de la Rubia Ortí JE, Barrios C, Mariscal G, Lorente R. Predictive Factors of Functional Outcomes and Quality of Life in Patients with Ankle Fractures: A Systematic Review. J Clin Med. 2024 Feb 20;13(5):1188. doi: 10.3390/jcm13051188. PMID: 38592026; PMCID: PMC10932135. 18. Tian J, Miao J, Jiang Z, Li Z. Comparison of operatively and nonoperatively treated isolated Weber B ankle fractures: a systematic review and meta-analysis. J Orthop Surg Res. 2024 Jun 10;19(1):346. doi: 10.1186/s13018-024-04835-4. PMID: 38858737; PMCID: PMC11163742.

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