Acute Achilles tendon rupture : predictors for outcome and plan for intervention

Acute Achilles tendon rupture (ATR) is a common tendon injury. Regardless of the initial treatment, many patients experience persistent symptoms and muscle weakness following ATR. This thesis aims to improve patient outcomes by identifying novel, modifiable, or preventable factors and subsequently plan an intervention study. The research questions addressed are: 1) What are the current incidence and treatment rates of ATR in Sweden? 2) Does the time between injury and surgical treatment affect patient outcomes after ATR? 3) Does the development of a deep venous thrombosis (DVT) during ATR immobilization impair patient outcomes? 4) To what extent does muscle deconditioning occur six weeks post-ATR, and how does it impact patient outcomes at one year?

To investigate trends in ATR incidence and treatment in Sweden, a nationwide register-based study was conducted, including all adult in- and out-patients between 2002 and 2021. Over this period, the long-term incidence of ATR increased by 45%, from 28.8 in 2002 to 41.7 in 2021 per 100 000 person-years (p<0.0001), an increase in ATR cases from 2025 per year to 3453 per year. Concurrently, the surgical treatment rates decreased from 13.4 to 6.0 per 100 000 person-years (p<0.0001), with only 15% of ATR cases surgically treated in 2021. Notably, the time from injury to surgical treatment (TTS) increased significantly by 719% throughout the study period, rising from approximately one day in 2002 to five days in 2021 (p<0.0001).

Next we examined the impact of TTS on patient outcomes and complications. A total of 228 ATR patients treated with a uniform surgical technique were retrospectively assessed. Patients were categorized into three TTS groups: < 48 hours, 48-72 hours, and >72 hours. Among those operated within 48 hours, 71% achieved a "good outcome", defined as an Achilles Tendon Total Rupture Score (ATRS) greater than 80. In contrast, only 44% of patients operated on after 72 hours reached this outcome. Additionally, the incidence of adverse events was significantly lower in patients treated within 48 hours compared those treated between 48 and 72 hours, and beyond 72 hours (1.4%, 11%, and 14.8% respectively).

The effect of DVT on patient outcomes was then investigated in 251 surgically treated ATR patients who underwent duplex ultrasound screening for DVT at discontinuation of immobilization. The overall incidence of DVT was 49% (122 out of 251). Patients who developed a DVT reported significantly lower ATRS one- year post-injury compared to those without DVT (ATRS 76 vs. 83, p<0.01). Moreover, patients with a DVT did not reach a "good outcome" to the same extent as patients without a DVT (51% vs 67%).

To assess muscle deconditioning post-ATR and its impact in one-year outcomes, 15 patients underwent computed tomography scans six weeks after lower leg immobilization. Cross-sectional area (CSA) and radiological attenuation (RA) were measured, with lower values indicating muscle loss and muscle fat infiltration (MFI), respectively. CSA and RA values were significantly lower in 2 out of 7 and 6 out of 7 muscles respectively, in the injured compared to the uninjured lower leg. RA was most notably reduced in the triceps surae and its individual muscles, while CSA was only significantly reduced in the lateral and medial gastrocnemius, with decreases of 23% and 20% respectively. Notably, lower RA values, i.e. increased MFI, in the injured triceps surae were associated with impaired functional outcomes one-year post-injury, while CSA reductions did not demonstrated any significant relationship with outcomes.

Given these findings, efforts should be made to mitigate the development of DVT and MFI during ATR immobilization. Intermittent pneumatic compression (IPC) is an intervention that aims to enhance blood circulation, decrease inflammation and provide muscle stimulation during immobilization. The Swedish multicenter Trial of Outpatient Prevention of Leg Clots (STOP Leg Clots) is a prospective multicenter superiority trial, investing IPC during lower leg immobilization after ATR and ankle fracture. The primary aim to reduce venous thromboembolic events (VTE), while secondary aims include reducing MFI, enhancing healing and improving patient outcomes. VTE is defined as either symptomatic pulmonary embolism or symptomatic DVT, or ultrasound detected DVT detected at immobilization discontinuation. Patients will be randomized to the intervention or treatment-as-usual. With 90% power and an estimated 8% absolute risk reduction, a sample size of 700 patients per arm was calculated.

Conclusion

The incidence of ATR in Sweden has significantly increase and continues to rise. Delayed surgical intervention negatively impacts patient-reported outcomes and should be accounted for when comparing treatment strategies. ATR immobilization increases the risk of both DVT and MFI, significantly impacting patient outcomes. Preventive measures should be prioritized to optimize patient outcomes. The STOP Leg clots study, a ongoing prospective multicenter trial, aims to mitigate these negative effects and improve long-term recovery in ATR patients.

List of scientific papers

I. Svedman S, Marcano A, Ackermann PW, Felländer-Tsai L, Berg HE. Acute Achilles Tendon Ruptures Between 2002-2021: Sustained Increased Incidence, Surgical Decline and Prolonged Delay to Surgery - A Nationwide Study of 53,688 Patients in Sweden.
https://doi.org/10.1136/bmjsem-2024-001960

II. Svedman S, Juthberg R, Edman G, Ackermann PW. Reduced Time to Surgery Improves Patient-Reported Outcome and decreases the Risk of Adverse Events after Achilles Tendon Rupture. Am. J Sports Med. 2018, 46(12), 2929-2934.
https://doi.org/10.1177/0363546518793655

III. Svedman S, Edman G, Ackermann PW. Deep venous thrombosis after Achilles tendon rupture is associated with poor patient- reported outcome. Knee Surg Sports Traumatol Arthrosc. 2020;28(10):3309-3317.
https://doi.org/10.1007/s00167-020-05945-2

IV. Svedman S, Heijkenskjold M, Berg HE, Ackermann PW. Early lower leg muscle deconditioning after Achilles tendon rupture. [Manuscript]

V. Svedman S, Alkner B, Berg HE, et al. STOP leg clots-Swedish multicentre trial of outpatient prevention of leg clots: study protocol for a randomised controlled trial on the efficacy of intermittent pneumatic compression on venous thromboembolism in lower leg immobilised patients. BMJ Open. 2021;11(5):e044103.
https://doi.org/10.1136/bmjopen-2020-044103