Introduction

Acute distal biceps tendon ruptures are typically seen in middle-aged men (40–60 years old) in their dominant arm [5, 7, 9, 12, 15, 18, 23]. These injuries often occur when the biceps undergoes an excessive eccentric contraction, as the arm is forced from flexed to an extended position. There is an increased rate of ruptures among athletes, especially in contact sports and high-load resistance training programs [4, 18]. Pre-existing tendinosis, mucoid degeneration, and a decreased vascularity are believed to make the tendon more vulnerable to rupture [18]. Use of anabolic steroids, elevated body mass index (BMI), and smoking increases the risk of tendon rupture [11, 15, 18, 23] Surgical fixation is the preferred method of treatment for most distal biceps tendon ruptures, especially in active patients with an acute rupture. However, nonsurgical management can be justified in patients who are willing to accept some loss of endurance and strength of the affected arm. Without surgical repair, a reduction of supination (79%) and flexion (30%) endurance, and supination (21–55%), flexion (10–40%), and grip (15%) strength can be expected [7, 9, 12, 15, 17, 18, 22, 23]. However, some studies suggest a more modest reduction of supination strength (3%) in nonoperative treatment as compared with surgical repair [8].

Different surgical fixation methods exist, including: suture anchors, bone tunnels, interference screws, cortical button, or a combination thereof [9, 12]. The single-incision anterior approach or the double-incision approach are both practiced and their use depends on the fixation method and preference of the surgeon [5, 7, 9, 10, 12, 24]. Complications and range of motion after repair of an acute biceps tendon rupture have been extensively reported [7, 12, 19]. The risk of having a complication differs based on surgical approach, but does not seem to be related to the method of fixation. Patient-reported outcomes such as physical function have been studied less extensively. Establishing these outcome measures in this patient population helps us better understand how patients do after surgery. In addition, it will help us compare surgical techniques using an outcome measure relevant to patients and assess other possible determinants of functional outcome. This eventually could help us better inform future patients, and improve our shared decision making with the patient [17].

The primary aim of our study is to assess physical function and quality of life among patients who underwent repair of a distal biceps tendon rupture. Subsequently, we compared these patient-reported outcome measures between the two techniques practiced at our institution: suture anchor fixation and cortical button fixation. In addition, we studied the impact of other factors—acute versus chronic tendon repair, use of an interposition graft, presence of other concomitant arm conditions, contralateral distal biceps tendon rupture, and having a postoperative complication—on these outcome measures.

Methods

Study design and setting

This retrospective survey study was approved by our local ethics committee. We retrospectively reviewed the medical records of all patients with a distal biceps tendon rupture who visited our institution and underwent surgical repair between January 1, 2009 and December 31, 2016. We identified potentially eligible patients using diagnostic and procedure codes. We included all patients 18 years or older who underwent a distal biceps tendon repair within the 8-year period. There were no exclusion criteria.

We approached all patients by telephone or mail and invited them to participate voluntarily and complete a survey (either in Dutch or English) between August 21, 2017 and October 9, 2017. Informed consent was implied upon completion of the survey.

Study subjects

Fifty patients underwent distal biceps tendon rupture repair of 51 elbows within the 8-year period at our institution. One patient died before the start of this study due to a cause unrelated to the distal biceps tendon rupture. Of the remaining 49 patients, 11 (22%) patients could not be reached, and 1 (2%) patient declined to participate. Hence, 37 (76%) of the possible 49 patients participated in this study and completed the survey. There were 35 patients (95%) who completed the questionnaires in Dutch, and the remaining 2 patients (5%) completed the questionnaires in English. For statistical analysis purposes, we only considered the first distal biceps tendon rupture repair in the patient with two subsequent distal biceps tendon ruptures [2]. There was no difference between patients who participated in the study (n = 37) and those who did not (n = 13) with regards to: sex (p = 0.999), age (p = 0.903), systemic comorbidities (p = 0.173), fixation technique (p = 0.999), graft use (p = 0.999), affected arm (p = 0.999), time from injury to surgery (p = 0.486), or follow-up time (p = 0.558).

Within our study period, there were 19 patients with a ruptured distal biceps tendon who did not undergo surgical repair and were excluded from this study. It is unclear if any of these were partial ruptures. There was no difference between patients who underwent a distal biceps tendon repair (n = 50) and those who did not (n = 19) with regards to: sex (p = 0.275) or time from injury to presentation (p = 0.211). However, we did find a difference in age (p = 0.016): patients who elected not to have surgery (median age: 55 years, IQR: 44–62, range 30–69) were older than those who did undergo surgery (median age: 47 years, IQR: 40–52, range 27–65).

Minimum length of follow-up—calculated from the date of surgery until the time of survey completion for this study—was 8 months, with a median follow-up of 34 months (IQR: 19–49, range 8–100 months).

Surgical technique

Depending on the preference of the operating surgeon, suture anchors or a cortical button was used for fixation of the distal biceps tendon. There were four types of suture anchors used: Mitek in 7 patients (DePuy Synthes, Norwood, USA), Juggerknot in 13 patients (Biomet, Warsaw, USA), Bioraptor in 1 patient (Smith&Nephew, Memphis, USA), and Orthofix in 1 patient (Orthofix, Lewisville, USA). There was one type of cortical button used: the Endobutton (Smith&Nephew, Memphis, USA).

All patients were placed supine on the operating table with their affected arm on an arm table. The anterior approach was used in all patients using a single longitudinal or S-shaped incision distally from the antecubital fossa. The basilica vein and lateral antebrachial cutaneous nerve were protected. The distal biceps tendon was identified, and the degenerated distal tendon fibers were removed. The bicipital tuberosity was exposed by retracting the brachioradialis and the pronator teres and cleaned. The biceps tendon was retracted and pulled onto the tuberosity. The tendon was either fixated with suture anchors or a cortical button, depending on the surgeons preference. In three (6%) patients, there was a second anterior incision made more proximally, to retrieve the retracted biceps tendon. In five (14%) cases, a graft was used for interposition, in four of these an achilles tendon (allograft) was used and in one a semitendinosus (autograft) was used. All interposition grafts were combined with the endobutton technique. In a few cases a sterile tourniquet was used and in most cases prophylactic antibiotics were given.

Postoperative rehabilitation

Postoperative rehabilitation varied substantially and depended on the surgeon. In general, a cast was used for 2–8 weeks, or immobilization in a sling for 6 weeks. This was followed by a brace, 2–3 months of non-weight bearing, or no active flexion for 6 weeks. All patients were advised physiotherapy, seven patients declined physiotherapy. Median physiotherapy sessions per patient was 10 (IQR: 6–20).

Explanatory variables and outcome measures

We reviewed medical records for baseline characteristics: age, sex, affected arm, time from injury to surgery, other upper extremity injuries/conditions, systemic comorbidities, surgical approach, fixation method, graft use, postoperative rehabilitation protocol, complications, reoperation, and re-rupture. An injury was defined as chronic when the repair was done more than 28 days after injury.

The study survey included the following patient-reported outcome measures in the following order: the shortened version of the Disabilities of Arm, Hand, and Shoulder questionnaire (QuickDASH), the Mayo Elbow Performance Score, the Quality of life EQ-5D-5L and pain score using a numeric rating scale from 0 to 10, asking: “How intense was your average pain in the past 7 days?”. Patients also completed questions that provided more insight in baseline characteristics: BMI, systemic comorbidities, work, smoking, steroid use, sports, hand dominance, affected arm, mechanism of injury, postoperative physiotherapy, complications, re-rupture, and satisfaction after surgery.

The QuickDASH measures patient perceived upper extremity function and symptoms in people with musculoskeletal disorders of the upper limb. It contains eleven questions (e.g., are you able to open a tight or new jar?), with an outcome score between 0 and 100. A higher score indicates more disability.

The EQ-5D is a standardized non-disease specific instrument developed to describe and value health-related quality of life. The 5-level EQ-5D version (EQ-5D-5L) includes 5 dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension has 5 levels, reaching from no problems (level 1) to extreme problems (level 5). These 5 dimensions can be combined into an index score to describe a patient’s health state. The index score is calibrated for the Dutch population and runs from − 0.329 to 1.0 [20, 25]. The higher the index score, the better the patient’s quality of life.

The Mayo Elbow Performance Score (MEPS) is a performance index for clinical assessment of elbow function. It consists of 4 questions which assess pain, range of motion, stability, and daily function of the elbow. With a maximum score of 100, a score of 90 points or more equals excellent function, 89–75 points equals good function, 74–60 points equals fair function, and less than 60 points equals poor function of the elbow [6, 13].

Statistical analysis

A median with interquartile range (IQR) was used to describe continuous variables and absolute numbers with percentages were used to describe categorical variables. We also presented the percentage of patients who had perfect upper extremity function (QuickDASH = 0), perfect clinical elbow function (MEPS > 90), perfect quality of life (EQ-5D-5L = 1), and no pain (pain score = 0). We used nonparametric description of continuous variables and nonparametric tests as most variables were non-normally distributed.

Baseline and surgical characteristics were compared using the Fisher Exact test for categorical variables and the Mann–Witney U rank sum test for continuous variables.

Outcome measures were compared between study groups using the Mann–Witney U rank sum test.

A two-tailed p value of < 0.05 was considered to be significant. Statistical analysis was performed using Stata 14.0 (StataCorp, USA). Missing values (described in table legends) were excluded from statistical analyses.

Results

Baseline characteristics

All 37 patients were men, with an overall median age of 47 years (IQR 38–53, range 27–65) at the time of surgery (Table 1). The median time from injury until surgery was 11 days (IQR 5–35, range 2–263). Twenty-seven injuries (73%) were acute and 10 (27%) were chronic at time of repair. In seven patients (19%), the injury was work-related, 12 patients (32%) had ruptured their distal biceps tendon during sports, 2 (5%) had a traumatic event, and the remaining 16 patients (43%) ruptured their distal biceps tendon due to other causes. In total, 28 patients (76%) engaged in sports activities before injury; 7 (25%) played sports on a competitive level and 21 (75%) on a recreational level. The performed sports were: fitness (n = 15), boxing (n = 8), cycling (n = 6), martial arts (n = 4), weight lifting (n = 4), running (n = 3), rugby (n = 2), tennis (n = 1), skiing (n = 1), soccer (n = 1), swimming (n = 1) and rowing (n = 1). Overall, 4 (11%) patients had a prior history (n = 2) or future development (n = 2) of a contralateral distal biceps tendon rupture.

Table 1 Baseline characteristics at time of biceps tendon repair (n = 37)
Full size table

Of the 37 included patients, 22 (59%) underwent suture anchor fixation, and 15 (41%) underwent fixation with an endobutton. We found no difference between study groups based on age, BMI, sex, smoking, systemic comorbidities, acute versus chronic repair, or work type or intensity. However, we did find a higher rate of graft use in the endobutton group (33% versus 0% in the anchor fixation group) (p = 0.007). The mechanism of injury (p = 0.009) and sports level (p = 0.042) also differed between study groups.

Overall patient-reported outcome measures

On average, we found perfect upper extremity and elbow function, perfect quality of life, and no pain (Table 2). The QuickDASH questionnaire, completed by 36 patients, demonstrated an overall median score of 0 (IQR 0–7.9, range 0–66). The overall median EQ-5D-5L score (n = 37) was 1 (IQR 0.85–1, range 0.26–1). The overall median average pain score (n = 34) was 0 (IQR 0–0, range 0–8). The overall median Mayo Elbow Performance Score (n = 36) was 100 (IQR 100–100, range 40–100). However, there were a few outliers with poor upper extremity and elbow function, relatively poor quality of life, and substantial pain.

Table 2 Patient-reported outcome measures (n = 37)
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Overall, we found a perfect QuickDASH in 53% of the patients (n = 19), a perfect Mayo Elbow Performance Score in 83% of the patients (n = 30), a perfect EQ-5D-5L in 59% of the patients (n = 22), and no pain in 68% of the patients (n = 23).

Suture anchor versus endobutton fixation

We found no difference in upper extremity function (p = 0.972), quality of life (p = 0.507), pain score (p = 0.742), or elbow function (p = 0.895) when comparing the anchor to endobutton fixation technique (Table 2).

For anchor fixation, we found a perfect QuickDASH in 50% of the patients (n = 11), a perfect Mayo Elbow Performance Score in 86% of the patients (n = 18), a perfect EQ-5D-5L in 64% of the patients (n = 14), and no pain in 75% of the patients (n = 15).

For endobutton fixation, we found a perfect QuickDASH in 57% of the patients (n = 8), a perfect Mayo Elbow Performance Score in 80% of the patients (n = 12), a perfect EQ-5D-5L in 53% of the patients (n = 8), and no pain in 79% of the patients (n = 11).

Other explanatory variables

When comparing graft use to no graft use, we found no difference in upper extremity function, pain score, or elbow function. However, we did find a higher quality of life in patients without a graft (median: 1, IQR: 0.85–1), as compared to those with a graft (median: 0.84, IQR: 0.82–0.85) (p = 0.048) (Table 2). A graft was predominantly used in chronic ruptures (in 4 out of the 10 [40%] chronic ruptures, a graft was used; while only in 1 out of the 27 [3.7%] acute ruptures, a graft was used; p = 0.014). Despite this association, we found no association with timing of the repair with any of the patient reported outcomes.

When comparing patients with other arm conditions (e.g., subacromial pain syndrome) to patients without, we found no difference in upper extremity function, pain score or elbow function. However, we did find a higher quality of life in patients with no other arm conditions (median: 1, IQR 0.92–1) as compared to those with any other arm condition (median: 0.85, IQR 0.82–1) (p = 0.013).

Rupture of the contralateral tendon, and having a postoperative complication did not impact any of the patient-reported outcome measures.

Additional outcome measures

There were five (14%) complications documented, either in our medical records or by the patient upon completion of the survey. These complications were: (transient) lateral antebrachial cutaneous nerve palsy (LABCN) (n = 2), transient superficial radial nerve palsy (n = 1), subacromial pain syndrome (SAPS), and knee complaints after semitendinosus autograft surgery (n = 1). No patients underwent reoperation, and none of the included patients had a re-rupture. At the last follow-up (35 months), one patient documented ongoing sensory nerve palsy of his LABCN.

The median missed work days due to the rupture was 31 days (IQR 3–90, range 1–365). Of the 28 patients engaged in sport activities, 4 (14%) stopped or reduced their sporting activities because of their biceps tendon rupture at final follow-up.

Discussion

We aimed to assess patient-reported outcomes—including: upper extremity function, quality of life, pain, and elbow performance—in patients who underwent distal biceps tendon repair to help inform our patients and aid shared decision making. Overall, our study results indicate—on average—a perfect upper extremity and elbow function, a perfect quality of life, and no pain. We found no difference in patient-reported outcome scores between suture anchor fixation and cortical button fixation. Both groups had excellent outcome scores and reported minimal pain and disability at least 8 months after repair of their distal biceps tendon. Looking at other possible determinants of outcome, we found no difference in patient-reported outcome measures for: an acute versus chronic repair, presence of a contralateral distal biceps tendon rupture repair, or having postoperative complications. However, we did find worse quality of life in patients who had a graft, and in those with other concomitant arm conditions. These factors did not influence their upper extremity function, elbow performance, or pain scores.

There are several limitations of current study. First, we used retrospective collection of cases and the documentation of medical records is therefore not standardized, possibly leading to an underestimation of for example mild or transient complications. Second, we had some loss to follow-up; 76% of patients that underwent distal biceps repair participated in the study. However, we believe that our results are generalizable to all patients as there were no differences in baseline and surgical characteristics between participating and non-participating patients. In addition—except for 1 re-rupture within 3 months after surgery—there were no major complications documented for the patients who did not participate in our study. Third, during our study period there were also 19 patients who did not undergo repair of their ruptured distal biceps tendon. These patients were older than those who did undergo surgery. Fourth, decision for type of fixation depended on the surgeons’ preference for a specific technique. Difference, or absence of difference, might be related to the surgeons performing the surgery instead of the used technique or the differences in baseline. Fifth, we did not collect preoperative patient-reported functional outcome scores for our patients, so we are unable to establish improvement. Sixth, we did not perform objective measurements for supination and flexion function and strength, and range of motion. However, these outcomes have already been extensively reported, and subjective outcome measures such as patient-reported outcome measures are more relevant to the patient. Seventh, with our sample size we found no difference in QuickDASH between suture anchor and endobutton fixation; however, a larger sample size might have resulted in a significant difference. The effect size for this comparison was only 0.15, indicating a small effect. A post hoc sample size calculation—with an alpha of 0.05, a power of 0.80, and assuming a normal distribution with an effect size of 0.15—demonstrates that we would have needed 1644 patients in total to find a difference in favor of the endobutton fixation group (639 endobutton fixation, and 1005 with anchor fixation). Such a small effect would most likely be clinically irrelevant. Eight, we found a higher rate of graft use in the endobutton group, which might have biased our results leading to better results in the endobutton group without graft use. However, when excluding cases who had a graft, we found no difference in any of the patient reported outcome scores.

Overall patient-reported outcome measures in our study were on average excellent; however, there were a few outliers: one patient (with suture anchor fixation) had poor scores with a QuickDASH of 66, an EQ-5D-5L index score of 0.50, a pain score of 8, and a MEPS of 40. This patient had persistent pain in his wrist due to degeneration of his distal radioulnar joint, radio-carpal, and carpometacarpal joint of his first and second finger, which might be the main cause of these poor outcome measures. Another patient (with an endobutton and achilles tendon allograft) had poor scores with a QuickDASH of 64, an EQ-5D-5L index score of 0.26, and a MEPS of 65. This patient did not elaborate his complaints and has not documented complications or disorders in his medical records.

Many papers on distal biceps rupture repair report on range of motion, strength, and complications, while few report on subjective patient-reported outcome measures. Our study demonstrates a median QuickDASH of 0 and a median MEPS of 100, which indicates a perfect upper extremity and elbow function. This is comparable to previous studies. Redmond et al. [16] found a median QuickDASH of 2.25 and a median MEPS of 100 in 23 patients who underwent endobutton fixation of an acute rupture without use of a graft. Siebenlist et al. [21] found a mean QuickDASH of 7.9 in 49 patients who underwent suture anchor fixation of an acute rupture without use of a graft. As far as we know, there are no studies directly comparing patient-reported outcome measures between endobutton and anchor fixation [12, 26].

For a graft combined with endobutton fixation, we found a median QuickDASH of 9.1 and a median MEPS of 100, which indicates perfect upper extremity and elbow function on average. In comparison, Phadnis et al. [14] found a mean QuickDASH of 4 and a mean MEPS of 93 for the endobutton fixation technique combined with an achilles tendon allograft in 21 patients, which also indicates perfect upper extremity function and perfect elbow function.

For chronic repair, we found a median QuickDASH of 3.4 and a median MEPS of 100, which indicates perfect upper extremity and elbow function on average. In comparison, Bosman et al. [1] found a mean DASH of 4 and a mean MEPS of 100 for chronic repairs in 5 patients, which also indicates perfect upper extremity and elbow function.

The results of our study indicate perfect upper extremity function (QuickDASH and MEPS), a perfect quality of life (EQ-5D-5L), and no pain (pain score) on average after repair of a distal biceps tendon. Both techniques (anchor fixation and endobutton fixation) results in comparable outcomes, leaving the decision for surgical technique at the surgeon discretion. We did find worse outcome (quality of life) in patients who had repair with a graft, since grafts were predominantly used in chronic ruptures. The use of a graft for fixation of the biceps tendon has been associated with the treatment of chronic ruptures to regain tendon length. We therefore recommend—if surgery is considered—to perform distal biceps tendon repair within 4 weeks after injury [1, 3, 23].

Conclusion

Overall, distal biceps tendon rupture repair results in perfect upper extremity and elbow function, perfect quality of life, and no pain on average. We found no difference in these outcomes between two commonly used fixation techniques: suture anchor versus endobutton. We recommend repair within 4 weeks as graft use—which is more commonly done for chronic ruptures—is associated with worse quality of life.