Introduction

The frequency of distal biceps brachii tendon rupture (DBBTR) is 1-5/100,000 per year, and 96% of all traumatic DBBTRs originate from the long head, 1% from the short head, and 3% from the distal insertion of the biceps tendon (1). DBBTR usually occurs during weight lifting in men in their fourth or fifth decade of life and occurs in the dominant extremity as a result of eccentric loading of the muscle tendon unit (2). Smoking, anabolic steroid use, and intratendinal degeneration or hypovascularity are factors that increase the likelihood of this injury (3).

Surgical repair is applied as the first-line treatment in DBBTR, and tendon repair provides more successful and satisfactory results compared to conservative treatment (3-5). Therefore, surgical repair is recommended in active patients with DBBTR to restore elbow flexion and supination strength and to ensure limb endurance. Conventional single-incision or double-incision methods are used in distal biceps tendon repair (3).

The aim of this study was to compare the results of patients who underwent single incision cortical suspension system and tenodesis screw combination repair technique (6) and double incision bone tunnel repair technique (7) for distal biceps tendon repair. Our hypothesis was that the functional outcomes of treatments with different surgical techniques would be similar.

Methods

Before the start of the study, academic committee approval was obtained from the Bezmialem Vakıf University Orthopedics Department (no: 45446446-010.99-3655). The data of patients who underwent distal biceps tendon repair due to DBBTR between December 2012 and January 2018 were reviewed retrospectively. Patients with a follow-up of less than two years were excluded from the study. Acute injuries in active patients with a traumatic full-thickness tear on magnetic resonance imaging (MRI) and clinically accompanied by a decrease in supination muscle strength were considered as the indication for distal biceps tendon repair. Demographic information, extremity dominance, background and occupation of the patients participating in the study were documented. Consent was obtained from all patients for inclusion in the study. One of two different repair techniques was applied to all patients by a single surgeon (K.B.).

Preoperative Evaluation

Preoperative hook test (8) was performed on all patients with suspected distal biceps injury and MRI was requested for radiological evaluation of possible injury. Range of motions (ROM) of elbow flexion and extension, and forearm pronation and supination of the patients were measured preoperatively with a universal goniometer, and Mayo elbow performance scores (MEPS) were recorded. Patients without these assessments were not included in the study.

Surgical Technique

Informed surgical consent forms were obtained from all patients before surgery. All patients were operated in the supine position after full muscle relaxation was achieved under general anesthesia. Following the IV administration of 1 gram of cefazolin, the biceps muscle was stroked to the distal and a tourniquet was applied by extending the muscle length. All surgical procedures were performed on the swimsuit table after sterile staining and dressing. In patients with excessive biceps tendon retraction on MRI, a double incision technique was preferred, and in patients without tendon retraction, a single incision technique was preferred.

Anterior Single Incision

The skin and subcutaneous tissue were passed through a transverse 3-4 cm incision 3 cm distal to the elbow crease. After the skin incision, the lateral cutaneous antebrachial nerve adjacent to the cubital veins was dissected and suspended. The distal biceps tendon, which migrated proximally by blunt dissection, was found and the tendon tip was debrided and thinned. The tendon was prepared using the 4 cm Krackow suture technique with 2.0 Etibond (Ethicon, Somerville, NJ) suture. Then, to prepare the radial tuberositas, it was deepened by blunt dissection between the brachioradialis and pronator teres muscles. The bone was reached with the elbow extended and the forearm hypersupinated. The tendon stump was removed from the bone with the aid of a curette and a rongeur. After proper retraction, bone double cortex was drilled with a 3.2 mm drill bit for bone tunnel preparation. Then, the proximal single cortex was drilled 7-8 mm according to the tendon thickness. Tendon sutures were loaded onto the cortical suspension system (Smith & Nephew, Memphis, TN) and double cortex was bypassed. The sutures were stretched and the tendon was placed in the bone tunnel and tightened with a 1 mm thin tenodesis screw (Smith & Nephew, Memphis, TN) from the tendon at appropriate tension. Then, the tendon was sutured with the threads coming out of the cortical suspension system (Figure 1) (6).

Double Incision

With a 2-3 cm transverse incision made from the elbow bend, the skin and subcutaneous tissue were passed. After LACN dissection and tendon preparation, soft tissue resection was performed with blunt dissection. The location of the second 3-4 cm longitudinal incision to be made posterolaterally between the extensor carpi ulnaris and the extensor digitorum communis muscle interval with a blunt curved surgical instrument was determined using the inside-out method. The forearm was pronated and the posterior interosseous nerve (PIN) was removed. The radial tuberositas cortex was debrided with the aid of a rongeur and curette. The tunnel into which the tendon would enter was prepared with Burr. Three holes were drilled on the sides of the tunnel through which the sutures were to be passed, and 4 sutures, through which the tendon was sutured, were taken and passed through the posterolateral incision with the inside-out method. The tendon was fixed on the prepared place on the bone (Figure 2) (7).

Postoperative Rehabilitation

Postoperatively, the upper extremity of all patients was placed in a long arm plaster splint with the elbow in 90° flexion and the forearm in supination. Wound dressing was recommended every three days as a standard to the patients. The plaster splint was removed 2 weeks after the operation. Exercises to increase ROM with the support of gravity were started and the patients were recommended to use a shoulder arm sling for 2 weeks. Thirty degrees of active extension until the sixth week and full elbow extension at the second month were aimed. Active flexion and strengthening exercises were started in the second month. The patients returned to their daily lives after 3 months and were released for sports activities at 6 months.

Postoperative Functional Evaluation

Postoperative ROM and MEPS of all patients at the latest clinical follow-up were evaluated by a single physiotherapist. The two surgical techniques were compared with each other in terms of complications of heterotropic ossification (HO), radioulnar synostosis, infection, nerve damage, fracture, dislocation of the cortical suspension system, and re-rupture of the distal biceps tendon during clinical follow-ups.

Statistical Analysis

All statistical analyzes were performed using the SPSS statistical software package (IBM Corp.^© Released 2012. IBM SPSS Statistics for Windows, Version 21.0. Armonk, NY: IBM Corp.). Conformity of continuous data to normal distribution was evaluated by Kolmogorov-Smirnov test. Continuous variables were expressed as median (minimum-maximum) and mean ± standard deviation. Categorical variables were expressed as frequency (percentage) values. Continuous comparisons were made using the Mann-Whitney U test, and categorical comparisons were made using the Fisher-exact test. The results were reported as the respective p-values. P<0.05 was considered statistically significant.

Results

Demographic Results

The data of 28 patients who underwent surgery for DBBTR were reviewed retrospectively. Four patients with a follow-up period of less than 24 months, 3 patients who did not comply with the standard postoperative rehabilitation protocol, 2 patients who were operated for chronic tears, and 2 patients whose postoperative follow-up was not documented were excluded from the study. A total of 17 patients, 9 of whom were treated with the single incision technique and 8 with the double incision technique, with a follow-up period of at least 24 months were included in the study. The mean age of the patients was 45.6±6.4 (34-58), and the mean follow-up time was 33±10.5 (24-62). All patients with DBBTR were male. 13/18 (72%) of the patients were physically active working or doing sports. The dominant arms of 10 and the non-dominant arms of 7 of the patients participating in the study were injured. The mean time from injury to surgery was 2.1±1 (1-4) weeks. There was no difference between the two groups in terms of demographic characteristics (Table 1).

Functional Results

The mean MEPS of the patients increased from 78.2±12.2 preoperatively to 97.6±5.3 postoperatively. There was no significant difference between the groups in terms of pre- and postoperative ROM and MEPS (p>0.05) (Table 2).

Complications

No complications such as fracture, wound problem, infection, stiff elbow, HO, and synostosis occurred in any of the patients who underwent surgical repair due to DBBTR. Transient LACN palsy developed in 3 patients who were operated with a single incision technique and were followed up with conservative treatment. Revision distal biceps tendon repair was performed in 1 patient due to re-rupture in the second month after surgery. Transient PIN palsy developed in 1 patient who was operated with the double incision technique and recovered in three months with conservative treatment. One patient had a hematoma that did not require surgical drainage. There was no significant difference between the two groups in terms of complications (p=0.62).

Discussion

The important finding of our study is that both single incision and double incision techniques are reliable in the surgical treatment of DBBTR and these two techniques have similar results in terms of ROM, functional results and complication rates. The complication rate of both surgical techniques is low, and patients treated with the single incision technique are at risk for LACN and those treated with the double incision technique are at risk for PIN. In the case of neuropraxia due to injury to these nerves, successful results are obtained with conservative follow-up.

In cadaveric studies comparing the single and double incision technique in the treatment of DBBTR, it was claimed that the footprint restoration of the tendon with a single incision tended to be made more forward and this led to supination weakness. In addition, it was reported that footprint restoration with double incision repair was more anatomical (9,10). In contrast, Grewal et al. (11) found no difference in terms of ROM, functional score and supination strength between the two techniques, but flexion strength was found to be significantly higher in the double incision group in a randomized clinical study. Castioni et al. (12) showed that more flexion and pronation were obtained with the single incision technique in a meta-analysis comparing single and double incisions in which they included 2,622 patients. We found no significant difference in terms of postoperative ROM (pronation: 86.1°-88.8°, supination 85°-88.8°, flexion 141.7°-143.8°) and functional MEPS scores (98.3-96.9) between the two techniques.

The PIN injury is one of the most important complications of distal biceps repair (13,14). Amarasooriya et al. (15) reported that post-repair motor nerve injuries were found around 2% and most of them were PIN injuries in their systematic review of acute distal biceps tendon repair. However, they showed that 92% of PIN injuries healed with conservative follow-up. There was no difference between single incision (2/233) and double incision (6/411) in terms of PIN injury. Luthringer et al. (16) showed that the PIN injury due to single anterior incision in the repair of the distal biceps tendon might result from placing an improperly distal retractor, and that forearm supination during instrumentation was protective against this injury in an MRI study investigating the relationship between altered forearm rotation and the distance of the PIN from the radial tuberositace. Similarly, Dunphy et al. (17) reported that PIN damage was significantly higher in the double incision technique (3.4% vs 0.8%). In contrast, Amin et al. (14) found that PIN damage was more common in patients with single anterior incision compared to double incision (2.7-0.2%). In our study, although we did not find any postoperative PIN damage in 9 patients in whom we made a single anterior incision, transient PIN palsy developed in 1 of 8 patients who were repaired with a double incision. The patient recovered within 3 months with conservative follow-up. Similar to the literature, we think that a retractor should not be used towards the distal radius of the radius neck in order to protect from PIN damage and that long-term use of retractors should be avoided.

Although care is taken to preserve the LACN during distal biceps repair, the most common postoperative complication is related to this nerve. Although LACN injury is usually in the form of neuropraxia, the frequency of persistent LACN palsy ranges between 0.6% and 26% in the literature (18-21). Castioni et al. (12) found significantly less LACN injuries in patients who underwent double incision than in patients who underwent single incision. Amarasooriya et al. (15) found significantly more LACN damage in patients who underwent repair with a single incision compared to those who underwent double incision (9.3-5.8%). In our study, in parallel with the current literature, LACN damage was found in 3 of the patients who underwent repair with a single incision, and the nerve damage was healed within 3 months in all of these patients. LACN damage was not observed in any of the patients who underwent double incision. We think that double incision prevents traction damage.

Finally, regarding the method of fixing the tendon to the bone, the cost of materials such as screws, anchors (22,23) or cortical suspension system (24,25), which are more expensive than standard sutures, should be considered. In our study, the cortical suspension system and tenodesis screw used in the single incision technique caused additional costs. In this regard, Grant  et al. (26) investigated whether the use of implants in DBBTR provided a shortening of the operation time enough to cover the additional cost of the implants. They found that there was no significant difference between the transosseous group and the anchored group in terms of operation time. However, they emphasized that the cost of the anchor should be taken into account.

Study Limitations

There are many limitations of our study. First of all, a limited number of patients were included in the study and the data were reviewed retrospectively. The fact that all surgeries were performed by a single surgeon could also be considered as a limitation. Another limitation was the inability to measure muscle strength before and after surgery. Another limitation was that double incision was preferred in injuries with excessive tendon retraction and single incision repair in injuries without tendon retraction. Finally, the physiotherapist’s inability to be blinded to the treatment performed in the postoperative functional evaluation due to the existing incision scars could be considered as a limitation.

Conclusion

Both single and double incision techniques are reliable in DBBTR. The results of both techniques are similar in terms of functional score, ROM and complications, but PIN in double incision technique and LACN in single incision technique are at risk. In the future, prospective, randomized studies with more patients will shed light on which technique is more advantageous.

Ethics

Ethics Committee Approval: Before the start of the study, academic committee approval was obtained from the Bezmialem Vakıf University Orthopedics Department (no: 45446446-010.99-3655).

Informed Consent: Informed surgical consent forms were obtained from all patients before surgery.

Peer-review: Externally peer reviewed.

Authorship Contributions

Concept: M.K., A.P., V.U., O.T., K.B., Design: M.K., A.P., V.U., O.T., K.B., Data Collection or Processing: M.K., A.P., V.U., O.T., K.B., Analysis or Interpretation: M.K., A.P., V.U., O.T., K.B., Literature Search: M.K., A.P., V.U., O.T., K.B., Writing: M.K., A.P., V.U., O.T., K.B.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declared that this study received no financial support.