Use of Frozen Tendon Allograft in Two Clinical Cases: Common Calcaneal Tendon and Patellar Ligament Rupture
ABSTRACT
Many surgical techniques have been described in the literature to repair chronic tendon or ligament ruptures. Although direct approximation of the edges is the surgical technique of choice, the use of synthetic, fascia lata, semitendinosus muscle, and small intestinal submucosa grafts has been described to repair large defects or augment tenous repairs. The aim of this paper was to present the long-term outcome of two clinical cases using a common calcaneal tendon cadaver allograft with subsequent application of platelet-rich plasma for chronic ruptures diagnosed by ultrasound, with a chronic defect between both edges. Twenty-four months after common calcaneal tendon rupture and 12 mo after patellar ligament rupture, orthopedic follow-up of both patients showed complete functional recovery and ultrasound findings were consistent with correct integration of the graft in both cases.
Introduction
Tendon injuries are rare in cats and dogs and can lead to complete or partial ruptures. They are usually traumatic in origin but may also be iatrogenic or result from progressive degeneration.1
The most characteristic clinical sign of traumatic Achilles tendon rupture is tarsal hyperflexion on stifle extension, together with plantigrade stance of the limb. If the tendon injury is chronic or partial, the degree of tarsal hyperflexion can vary.1,2 The main symptoms of patellar ligament ruptures are severe limping due to a breakdown of quadriceps function, local swelling and pain, laxity of the ligament, and proximal dislocation of the patella.3
Clinical diagnosis is established from the medical history and orthopedic examination. Radiograph study is useful to exclude bone abnormalities or soft-tissue mineralization that may affect treatment decision. It is generally confirmed by ultrasound (US), which, in addition to being useful in postoperative follow-up of the healing process, also allows differentiation between partial and complete ruptures.4
Medical treatment by external support is recommended only in cases of chronic degeneration or partial ruptures, as the results are unpredictable.2,4 Thus, surgical repair together with immobilization of the joint is usually advocated.3,5,6 In the case of chronic ruptures or ruptures that do not allow edge apposition, the use of fascia lata grafts and biological and artificial implants has also been reported.7–14 In human medicine, successful surgical repair using Achilles tendon allografts has been described.15,16 The use of coadjuvant therapies to accelerate the healing process and reduce the incidence of complications is recommended.17–19
The aim of this report was to describe the surgical repair and long-term outcome of two cases, chronic common calcaneal tendon rupture and patellar ligament rupture, by using Achilles tendon cadaver allografts from a canine bank and application of autologous platelet-rich plasma (PRP).
Case Report
Case 1
A 3 yr old intact male German shorthaired pointer was brought to the hospital with a history of lameness and plantigrade stance of the right hind limb following an injury 3 wk previously. A complete physical examination was carried out, in which all findings were normal, except the right hind limb lameness. On orthopedic examination, the patient was found to have plantigrade stance of the hind limb and tarsal hyperflexion on stifle extension. Palpation of the extremity revealed loss of continuity of the middle body of the Achilles tendon.
Additional tests included a radiological study of the right tibiotarsal region, with no notable bone abnormalities, and US of the common calcaneal tendon. The definitive diagnosis was complete rupture of the calcaneal tendon, with an 8 cm gap between both edges. The distal tendon end of the lesion was 3.4 cm from the calcaneus. Paratenon effusion was also observed.
Once the diagnosis was confirmed, surgical treatment was decided. Owing to the large defect, a frozen Achilles tendon allograft from a canine tissue bank was applied.
Preoperative study including hematology, biochemistry, chest radiographs, and electrocardiogram was normal.
On the day of the surgery, the patient was premedicated with dexmedetomidinea (5 µg/kg IV), methadoneb (0.2 mg/kg intramuscularly), robenacoxibc (2 mg/kg IV), and cefazolind (22 mg/kg IV); cefazolin was readministered 2 hr later. Anesthesia was induced with propofole (3 mg/kg IV) and maintained during the surgery with isofluranef and oxygen (0.4 L). Intraoperative analgesia was achieved with a fentanyl bolusg (5 µg/kg), followed by continuous perfusion (6 µg/kg/hr IV). Intermittent positive-pressure ventilation was applied during surgery.
The surgical procedure consisted of first immobilizing the tarsus. To achieve this, a caudolateral approach to the tarsus was made from the distal third of the tibia to the distal part of the calcaneus; a calcaneotibial cortical screw (3.5 mm diameter × 40 mm length) and smooth washer were subsequently applied, fixing the tarsus in a hyperextended position. The surgical incision was then extended to the middle third of the tibia to prepare the bed for the new tendon. The tendon sheath was identified, and both ends of the affected tendon (distal and proximal) were debrided.
The allograft was prepared simultaneously, adapting it to the final implant length and debriding the rest of the surplus tissue. The graft had been previously thawed at room temperature and steeped in 0.9% physiological saline under aseptic conditions.
The graft was applied by suturing the superficial and deep portions of the tendon using a modified Bunnell-Mayer suture pattern with commercial polyamideh, 0 for the proximal edge and 2/0 for the distal edge (Figure 1). Absorbable U-sutures were then applied with commercial 2/0 polydioxanonei to strengthen the attachment between both segments. Finally, the sheath was sutured along its entire length with absorbable U-sutures, using a commercial 2/0 polydioxanone suturei.
Citation: Journal of the American Animal Hospital Association 56, 6; 10.5326/JAAHA-MS-6870
Before closing the incision, autologous PRP was injected into the tendon in the area where the proximal and distal edges were attached and along the entire length of the sheath. The PRP was obtained by extracting venous blood from the patient’s jugular vein into 4.5 mL Vacutainer tubes containing sodium citrate, in aseptic conditions. Ten tubes were collected and then centrifuged at 210g for 10 min, obtaining approximately 10 mL of PRP. Fifty percent of the plasma fraction above the buffy coat was used, after discarding the first plasma fraction. The PRP was activated by adding calcium chloridej (5% of the total volume to be applied). Finally, the subcutaneous layer was closed with a continuous suture pattern, and the skin was closed in a conventional manner.
Postoperative X-rays taken in lateral and craniocaudal projection showed correct placement of the calcaneotibial screw. A fiberglass cast was then applied for the first 6 wk and checked weekly, but no complications were found. Postoperative medical treatment consisted of cephalosporind (22 mg/kg per os [PO] q 12 hr) for 14 days, metronidazolek (15 mg/kg PO q 12 hr) for 5 days, omeprazolel (0.7 mg/mL PO q 24 hr) for 21 days, fraxiparinem (50 IU/kg subcutaneously q 24 hr) for 15 days, robenacoxibc (1 mg/kg PO q 24 hr) for 21 days, and buprenorphinen (6 µg/kg PO q 8 hr) for 5 days.
After 6 wk, the calcaneotibial screw and washer were removed. The splint was changed for a Robert-Jones bandage, which was finally removed 10 wk after surgery. The dog commenced a 1 mo rehabilitation period with physiotherapy, beginning 8 wk after the surgery.
Orthopedic checkups were carried out at wk 2, 4, 6, 8, 10, and 12. There were no abnormal findings or complications over this time, apart from loss of muscle mass as a result of the patient resting and a mild weight-bearing lameness (2/5 according to the Jandi and Schulman classification) during wk 6 and 8, which gradually resolved with return to normal activity at wk 12. The normal range of tarsal articular mobility was observed after wk 10.
US checkups were carried out at wk 2, 4, 6, 8, 10, 12, and 24; evaluation criteria were the echogenicity of the proximal, medial (the allograft area), and distal tendon regions. The tendon sheath was also assessed, as were the suture attachment areas between the allograft and tendon edges. The US findings were consistent with patient recovery, observing correct integration of the graft. The first evaluation showed a small effusion around the allograft, which disappeared after 4 wk. The sutures were visible as hyperechoic foci in all the evaluations. The distal aspect of the tendon was thickened and mildly heterogeneous at the level of the sutures of the allograft in all the studies. The echogenicity and fiber pattern of the allograft were normal. One year after surgery, the left calcaneal tendon measured 8 × 6 mm (lateromedial × craniocaudal) at 3 cm from the calcaneus, and the right tendon measured 13 × 8 mm. Proximal and distal tendon regions showed heterogeneity at suture levels (Figure 2). The patient was brought to the veterinary center for re-evaluation at 6, 8, 12, and 24 mo after the procedure. The orthopedic examinations showed no abnormalities, and the patient was discharged.
Citation: Journal of the American Animal Hospital Association 56, 6; 10.5326/JAAHA-MS-6870
Case 2
A 1 yr old intact male Spanish greyhound was brought to the hospital with lameness of the right hind limb due to trauma 15 days previously.
A complete physical examination was unremarkable. On orthopedic examination, the dog was found to have severe right hind limb lameness. Palpation of the stifle joint was painful, and the area was swollen. Proximal displacement of the patella was observed, with loss of continuity at the level of the patellar ligament.
Additional tests included radiography of the stifle joint, which revealed proximal displacement of the patella, and US, which showed thickening of the patellar ligament (11 mm) in comparison with the contralateral limb, with 80–90% disruption of the fibers. Preoperative study including hematology, biochemistry, electrocardiogram, and chest radiographs showed no abnormalities.
The anesthesia protocol was the same as that in case 1. The surgical procedure started with a 10 cm medial parapatellar approach. Tissue was debrided partially until the healthy patellar ligament was seen. To minimize the forces of the quadriceps on the allograft, a 0.6 mm wire suture crossed on itself (total diameter 1.2 mm) was placed from the distal quadriceps tendon to the tibial tuberosity (tunnel diameter 1.5 mm). The rest of the surgical technique and preparation of the allograft were the same as those for case 1 (Figure 3).
Citation: Journal of the American Animal Hospital Association 56, 6; 10.5326/JAAHA-MS-6870
The surgical procedure was completed with immobilization of the stifle joint. A transarticular external skeletal fixator was applied (2 mm Kirschner pin × 4 mm connecting bars) for immobilization. Postoperative X-rays were taken in lateral and craniocaudal projections to confirm that the pins were well placed. Two weeks after surgery, the external fixator was removed, and a fiberglass cast (spica) was placed for 2 wk; finally, a Robert-Jones bandage was applied for a further 2 wk.
Postoperative medical treatment and orthopedic and US follow-up criteria were the same as in case 1. The US findings were consistent with patient recovery, observing correct integration of the graft, where the sutures were visible as hyperechoic foci. One year after surgery, the right and left patellar ligaments had a thickness measuring 8 mm and 2 mm, respectively (Figure 4). All ligament regions showed heterogeneity. The patient showed a mild weight-bearing lameness (1/5) at wk 6 after the Robert-Jones bandage was removed but with no pain during palpation. Normal gait was observed at wk 10. Twelve months after surgery, the orthopedic and US examinations were consistent with recovery, and the patient was discharged (Supplementary Video I).
Citation: Journal of the American Animal Hospital Association 56, 6; 10.5326/JAAHA-MS-6870
Discussion
Tendon ruptures in pets are rare. They can be complete or partial and can be traumatic (as in the cases presented here) or iatrogenic or result from progressive degeneration.1,2
The diagnosis of tendon and ligament ruptures is based mainly on physical examination.2,3,15,16 When these occur in the common calcaneal tendon, they are characterized by plantigrade stance of the affected limb.2,6 However, for partial ruptures, the physical examination may not be diagnostic. In the case of patellar ligament rupture, orthopedic exams may show local swelling, pain, and proximal dislocation of the patella.2,3 Although diagnosis by MRI is common in human medicine,15 US is the most widely used technique in veterinary medicine, as it is more economic and more affordable in daily practice. US can differentiate between complete and partial ruptures, measure the distance between the tendon edges, and confirm or rule out the existence of fluid or hematomas.4 In these cases, the US examination revealed a chronic large defect between the proximal and distal edges, which led us to consider surgical options different from the conventional approaches used in acute cases where primary tendon apposition is possible.
Surgery is recommended for acute ruptures. The preferred technique consists of first immobilizing the joint together with approximation of the tendon edges by tenorrhaphy in the case of tendon ruptures.6 Medical treatment by external coaptation has been described, although the results are generally less satisfactory.2,5 In these cases, it was ruled out owing to the complete rupture and extensive retraction of the edges.
In human medicine, besides the usual methods, reconstruction with an Achilles tendon allograft has been reported, with satisfactory results.15,16 In the cases presented, we decided to perform surgical repair using an allograft, given the chronicity of the conditions, with an 8 cm defect between the tendon edges in case 1 and enlargement of the patellar ligament (11 mm) with 80–90% disruption of the fibers in case 2. One of advantages of allografts compared with other options for repairing tendon defects is the replacement of one structure by another that is anatomically and histologically identical, which biomechanically offers great medium- and long-term advantages. Allograft was chosen over autograft because there is no need to obtain another tendon from the same patient and, in accordance, surgical times are reduced, also offering the possibility of choosing an appropriate size according to patient defect.
In human medicine, the most common complications associated with the use of allografts are immune-mediated reactions and subsequent rejection, disease transmission, and higher cost.15,16 In our cases, there were no complications associated with the use of the allograft.
The use of autologous PRP to accelerate tendon healing using the method described by Anitua et al.20 has been proved, showing an improvement in tendon healing and obtaining better functional outcomes in a shorter period of time.17–19 In these cases, the use of PRP was preferred over the use of other healing methods, such as stem cells, because the obtaining, activation, and application can be done in a short period of time, contrary to stem cell therapy, in which more time is necessary, as the extraction is performed before surgery under sedation and culture is needed. In the cases presented, based on the patients’ recovery and US follow-up, the use of PRP did not appear to have had any adverse effects, as there were no complications associated with its use. However, we cannot confirm its effectiveness because of the absence of a control group.
Immobilization of the joint to prevent distension forces can be achieved using screws, external fixators, or external coaptation, none of which have shown any advantage over the other. Apposition of tendon edges can be done on the basis of different types of sutures. In both cases, a modified Bunnell-Mayer suture was used because of the size and type of the tendon and because it also offers a good resistance to traction between both edges. Postoperative treatment of patients with tendon or ligament rupture is based on rest until fixation is removed, together with rehabilitation techniques.1,3,5,6
US is a good method for postoperative follow-up of tendon and ligament ruptures, as it enables the treated area to be evaluated visually. The formation of hematomas or free fluid, echogenicity of the different parts (ends and allograft), increase or decrease in the diameter repaired, and the sutures can also be assessed. However, the end of the healing process cannot be determined.4,21 In both cases, the parameters to be assessed were the echogenicity along the sheath and tendon edges, the areas where the allograft was sutured, and the presence or absence of free fluid. In any case, US follow-up of the patients was continuous, and there were no significant changes over the various visits, other than thickening of the treated tendon.
Conclusion
Surgical repair of a chronic complete tendon rupture and a chronic patellar ligament rupture using an allograft, plus the application of PRP, is an acceptable approach. It was not associated with complications in these cases, with both patients making a full recovery in 6 mo. Nevertheless, the evaluation of new cases and studies that include a control group are warranted to evaluate the long-term efficacy of using an allograft, its advantages over methods already described, and the importance of using PRP as a stimulant in its healing and integration.
Image of the allograft implantation to the proximal edge. The yellow arrow points to the distal edge of the allograft proximal portion. The green arrow shows the distal edge of the tendon.
Ultrasound image of the Achilles tendon allograft 12 mo after surgery comparing both limbs at proximal transversal view (A), distal sagittal view (B), and tendon sheath sagittal view (C).
Intraoperative picture of the tendon during its implantation. The yellow arrow shows the proximal patellar portion.
Ultrasound image of the patellar tendon allograft 12 mo after surgery comparing both limbs, right (A) and left (B) in a sagittal view. The patellar tendon is shown between yellow arrows.
Contributor Notes
PO (per os); PRP (platelet-rich plasma); US (ultrasound)
The online version of this article (available at jaaha.org) contains supplementary data in the form of one video.
