Reconstruct Flexor and Extensor tendon in Severe Hand Injury Using Allogenic tendon: A Retrospective study

Background To evaluate the effective and safety of reconstruction of flexor and extensor tendon in hand using allogenic tendon with 2- to 7.6-year fellow-up. Methods Between August 2007 and July 2014, we performed tendon allografts for 14 patients who suffered from severe hand injury with 2 or more tendon defects. 10 patients have been followed-up, 6 cases of flexor tendon rupture with defect, 3 cases of extensor tendon rupture with defect, 1 case with flexor and extensor tendon rupture with defect. Tendon allografts were used to repair tendon defects in order to reconstruct the function of flexion or extension. At the final follow-up visit, the total active motion (TAM), grip strength, pinch strength, DASH and the degree of satisfaction were measured. The WBC, C-reactive protein (CRP), Erythrocyte sedimentation rate (ESR), Total T cell and CD4+T/CD8+T were measured to evaluate the response related to immune and infection. The was months (range The TAM was (rang grip strength was (rang the score of was 14.25 (rang 3.3-30.8), 7 patients were satisfied and 3 patients with the results. The results of WBC, CRP, ESR, Total T cell and CD4+ T/CD8+ T were mostly in normal field.

2 Abstract Background To evaluate the effective and safety of reconstruction of flexor and extensor tendon in hand using allogenic tendon with 2-to 7.6-year fellow-up.

Methods
Between August 2007 and July 2014, we performed tendon allografts for 14 patients who suffered from severe hand injury with 2 or more tendon defects. 10 patients have been followed-up, 6 cases of flexor tendon rupture with defect, 3 cases of extensor tendon rupture with defect, 1 case with flexor and extensor tendon rupture with defect. Tendon allografts were used to repair tendon defects in order to reconstruct the function of flexion or extension. At the final follow-up visit, the total active motion (TAM), grip strength, pinch strength, DASH and the degree of satisfaction were measured. The WBC, C-reactive protein (CRP), Erythrocyte sedimentation rate (ESR), Total T cell and CD4+T/CD8+T were measured to evaluate the response related to immune and infection.

Conclusion
In severe hand injuries with multiple tendon defects, reconstruction of flexor and extensor tendon in hand using allogenic tendon is an effective and safe treatment.
Patients with severe hand injury are more common in the handicraft-intensive areas, which will bring great pain to patients and take great challenge to surgeon at the same time [1]. Patients with severe hand injury often include bones fracture, tendons, skin and other tissue injuries. Among this, many of them have tendon defect. For these patients, the most ideal way is to take the autologous tendon transplantation [2], but if patients who do not want to sacrifice autologous tendon or have multi-tendon defect, allogeneic tendon transplantation may be a good choice. Allogeneic tendon grafts have been used since the 1967 and proven to be effective [3], but have not been widely used due to concerns about immunogenicity and other issues. With the development of modern medicine, allograft tendon has been used in the cruciate ligament injury [4], Acromioclavicular ligaments injury [5] , Achilles tendon injury [6], hand trauma [7,8] and others widely. In this study, we report the efficacy and safety of allogeneic tendon graft used in severe hand injury patients with multiple tendon defects.

Methods
This study was approved by our institutional review board and informed consent was obtained from each participant. Between August 2007 and July 2014, we performed tendon allografts for 14 patients who suffered from severe hand injury the modified hand injury severity score [9] > 50 with two or more tendon defects. 10 patients have been followedup, including 3 females and 7 males with an mean age of 38.0 (range, 18 to 60) years at the time of the surgery.
Among the 10 patients, 9 were industrial accident and 1 utility knife cuts. Among all the patients, 6 cases of flexor tendon rupture with defect, 3 cases of extensor tendon rupture with defect, 1 case with flexor and extensor tendon rupture with defect. Except for tendon partial defects in all patients, they also have soft tissue or bone injuries. More details about patients are presented in Table1.

4
The allogenic tendons were off-the-shelf products in China. They were harvested and process by a commercial company (tissue bank of the Orthopedic Institute of the People's Liberation Army in Beijing) with strict guidelines and stored in deep-freeze environment.
Before surgery, we confirmed that patients have well healed wounds, pliable skin and soft tissues, no sign of infection and joint of the hand or wrist mobility can reach as normal passively. In preoperative communication, the patient with two or more tendon defects and does not wish to donate his or her own tendons were choice to tendon allograft (determined by patient after the risks and benefits of tendon allograft were described).
During surgery, the allogenic tendon was reconstituted with normal temperature saline with Gentamicin for 30 minutes before use transplantation into receptor. The rest of the surgical procedure is the same as autogenic tendon transplantation and ensure the tension of tendon suture is appropriate.
In flexor tendon graft, the tension should allow the repaired finger to appear slightly more flexed than the normal cascade and during the time of wrist flexion the finger can straight freely. When repaired the extensor tendon, we should keep the digit and wrist straighten and permit the finger flex as the wrist dorsal flexion.

Postoperative care
In Extensor tendon graft repair, the joint of wrist was dorsiflexion about 30° and the metacarpophalangeal(MCP) joint was straight with volar splint. In flexor tendon graft repair, the wrist and MCP joints were flexed about 30°and the joint of finger were slight flexion with dorsal splint. If flexor and extensor tendons were repaired at the same time, the wrist was fixed in neutral position.
After tendon graft, surgeon, patient, and rehabilitation physician have to be in regular cooperation to ensure the best outcome. We encourage patients to do limited range of passive motion 3 to 5 days after surgery. After 3 weeks, full range of passive motion and 5 limited range of active motion began. Full range of active motion began after 6weeks.

Outcome assessment
The total active motion (TAM) system [10] was used to evaluate the functional outcomes.
The motion of MCP, proximal (PIP) and distal interphalangeal (DIP) joints may be all affected in our series, so the active motion of three joints were measured for each injured finger. The TAM outcome use the sum of MCP, PIP joint and DIP joint flexion (in attempted fist position) minus the extensor lag at these joints(in thumb, TAM is the sum of MCP and interphalangeal joint flexion minus the extensor lag at these joints).
We also measured the grip strength of injured hand and pinch strength of injured finger.
The white blood cell (WBC), C-reactive protein (CRP), Erythrocyte sedimentation rate (ESR), Total T cell and CD4+ T/CD8+ T [11] were measured to evaluate the response related to immune and infection. At last, the degree of satisfaction with functional recovery of tendon allografts was asked (satisfied, partially satisfied, or not satisfied).

Results
The average follow-up period was 50.0 months (range 24-82 months) and wounds were well healed. No deep infection, infectious disease transmission or obvious immune rejection was found in these series. The mean motion of TAM was 129.9° (rang 12-259°), pinch strength was 0.76Kg (rang 0-4.5Kg), grip strength was 18.67Kg (rang 4-46Kg), the score of DASH was 14.25 (rang 3.3-30.8), 7 patients were satisfied and 3 patients were partially satisfied with the results ( Table 2). 5 patients received an immune-related blood test WBC, CRP, ESR, Total T cell and CD4+ T/CD8+ T. The results related to immune were mostly in normal field and details were presented in Table 3.

Discussion
The process of treatment for sever hand injury is complexity. Sometimes we usually have 6 to do several surgeries in order to recover the function of the hand. Before tendon graft, we may do surgery like internal fixtation, Vascular nerves or wound repair. After initial surgery we need to prevent the occurrence of infection, 1 case in our series was infected and after treated we do functional reconstruction. Generally speaking, functional reconstruction was usually taken 3 months after the wound healed.
The patients with severe hand injury may have several tendon defects, and we have to reconstruction it with tendon graft [7]. Weather to use allegnic tendon for reconstruction, we choose it according to the patient's intention. Some patients may choose allegnic tendon graft for worrying about their own normally functioning decreased after sacrifice tendon. Use allogeneic tendon can restore the continuity of tendon defective quickly and without restrict of the number autologous tendon can offer.
However, tendon allografts are not without some disadvantages [12]. Tendon allografts have the risk of rejection and disease transmission and this is one of the reasons that allogeneic tendons have not been widely used. But with the advances in tissue processing such as acellularization and extensive donor screening for transmissible diseases, it is time for us to address the reconstructive needs of patients with allogeneic tendon for multiple tendon defects. We used allograft tendons provided by the professional tissue transplant library and they use γ sterilization treatment which can mostly eliminate the spread of the disease. Before the allograft tendon was implanted into the receptor, it was invade in gentamicin water for 30 minutes. At the same time, no signs of transmission of infectious diseases were found in our study. In results of Tang et al [13] published, no infectious disease transmission, deep infection, or obvious immune rejection occurred in 24 patients who received tendon allografts. In addition, no evidence of immune reactions or disease transmission in Harner's [14] study with 3 to 5 years fellow-up. CD4+ T/CD8+ T which was considered related to tendon immune [11] was mostly normal as we measured.
Other measurement related to immune such as WBC, CRP and ESR were mostly in normal field of 5 measured patients. Therefore, we believe that it is safe to use allogeneic tendons. Besides, DeGeorge et al [15] and Drake et al [1] were also hold optimistic opinion about the application prospect of allogenic tendon.
Even with optimum surgical treatment and physical therapy, postoperative adhesion formation especially in allograft is also the fundamental problem which continue to challenge the hand surgeon [16]. In our series, one patient was adhesion and do release with flap shaping after 3 months, but the final function is still poor. Therefore, postoperative effective rehabilitation exercise, to prevent adhesion is extremely important. Even though we have always stressed the importance of rehabilitation exercises to patients, but when some patients discharge from hospital it is difficult to achieve it.
Before we decide to transfer the tendon, we must make sure the condition of tissues is permitted and the joint of the finger are not stiffness. Severe hand injury are often accompanied by multiple tissue injuries. So, the tendon transfer were usually performed in a two-stage procedure [16 17], with separate consideration given to the recovery of softtissue coverage. In Severe hand injury, the tendon graft was usually taken after the skin defect was covered 3 month later [17]. At the same time, the patient should exercise to avoid the joint stiffness. In our study, we performed the surgery 3.5months after wound healed and induct patient do exercise to avoid the joint stiffness during this period.
The goal of surgery is to restore hand function. We hope that patients will able to flex and extend their fingers freely. Although 3 cases of functional recovery were poor in our follow-up cases, we can hold the opinion that tendon allografts can restore the patient's function at some extent on the whole. Of course, the functional recovery of patients with severe hand injury is affected by many factors. In our study, some patient's injury was 8 indeed serious and has to receive multiple operations. For example, one case had internal fixation for phalangeal or metacarpal fracture, amputation of middle and ring at DIP level and anterolateral thigh flap repaired the wound at first stage. And then, the allogeneic tendon was transplanted at second stage. Finally, due to the serious injury, functional recovery is not ideal. In addition, patients with poor postoperative compliance and functional rehabilitation are not in place, which is also a problem. These tips require our clinicians to fully understand their strengths and weaknesses about tendon allografts before use it. It is very important to grasp the indications. If the patient have severe injury or unable to cooperate after surgery, use it with caution. In patients who have used allogeneic tendon repair, they must have regular follow-up visits and timely and effective functional exercise.

Conclusion
In severe hand injuries with multiple tendon defects, reconstruction of flexor and extensor tendon in hand using allogenic tendon is an effective and safe treatment. Informed consent was obtained from the patient whose data are provided.

Availability of data and materials
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Competing interests
The authors declare that they have no competing interests.

Funding
No funding was received.  "-" have not measured