ISSN - Versão Impressa: 0102-3616 ISSN - Versão Online: 1982-4378

Acesso aberto Revisado por pares
Original Article

Allograft of the knee extensor in cases of patellar tendon rupture in total arthroplasty patients

Transplante de aloenxerto de aparelho extensor do joelho em casos de rotura do tendão patelar em pacientes com artroplastia total

Fernando Fonseca



OBJECTIVE: Retrospective study to evaluate the functional results of patients with total knee arthroplasty and rupture of the patellar tendon, submitted to transplantation of the extensor knee apparatus with fresh frozen allograft.
METHOD: Nine patients, operated between 2003 and 2015, with a minimum of one year of follow-up. All patients were reviewed by performing a functional evaluation using the Knee Society score. Preoperative values were compared with those of the final evaluation.
RESULTS: Mean survival was 2.7 ± 1.9 years (14-1). The knee score improved from 38 ± 4.5 to 70 ± 8.5, and functional score from 30 ± 6.5 to 90 ± 3.5. Mean extension deficit was 5 (1-15). Mean range of motion was 80 (60-100).
CONCLUSION: The use of allograft is a solution for extreme cases of patellar rupture after total knee arthroplasty, providing reasonable functional results and representing an alternative to knee arthrodesis.

Rupture; Patellar ligament; Knee arthroplasty; Transplantation; Allografts.


OBJETIVO: Estudo retrospectivo para avaliação dos resultados funcionais de pacientes com artroplastia total do joelho e rotura do tendão patelar submetidos a transplante total de aparelho extensor do joelho congelado.
MÉTODO: Nove pacientes, operados entre 2003 e 2015, com um mínimo de um ano de seguimento. Procedeu-se a uma avaliação funcional com o escore da Knee Society, compararam-se os valores no pré-operatório e na última avaliação.
RESULTADOS: Sobrevida média de 2,7 ± 1,9 anos (14-1). O escore joelho melhorou de 38 ± 4,5 para 70 ± 8,5 e o escore funcional de 30 ± 6,5 para 90 ± 3,5. Déficit de extensão médio de 5° (1° - 15°). Arco de movimento médio de 80° (60-100).
CONCLUSÃO: O uso de aloenxerto é solução, de recurso, para casos extremos de rotura do tendão patelar após artroplastia total do joelho, parece apresentar resultados funcionais razoáveis e apresenta-se como uma opção à artrodese do joelho.

Ruptura; Ligamento patelar; Artroplastia do joelho; Transplante; Aloenxerto.


Citation: Fonseca F. Allograft of the knee extensor in cases of patellar tendon rupture in total arthroplasty patients . 53(5):552. doi:10.1016/j.rboe.2018.07.004
Note: ☆ Study conducted at Serviço de Ortopedia, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal.
Note: 1 Guidelines from the Bone Tissue Bank of the Hospital and University Center of Coimbra, approved by the Portuguese Institute of Blood and Transplantation.
Note: 2 According to the protocol of the Orthopedic Department that anticipates knee radiographs on an anteroposterior view, lateral view at 30° of flexion, and a skyview of the patella with 30° of flexion.
Received: March 5 2017; Accepted: May 9 2017


Patellar tendon rupture in patients who have undergone total knee arthroplasty is a rare1,2 and highly disabling condition with diverse etiologies.3 Several treatments are available, from simple suture to allograft.4 The use of complete extensor apparatus allograft (tibial tuberosity, patellar tendon, patella, and quadricipital tendon) is an uncommon and technically challenging solution that presents acceptable results.5

This study is aimed at evaluating the authors' experience with this type of treatment.



A retrospective study with a mean duration of six years (1-14 years) was performed in nine patients who had undergone total knee arthroplasty and presented rupture of the patellar tendon, who then received a frozen complete knee extensor apparatus allograft. All patients were operated and followed by the author.

There were nine patients, two males and the remaining, females. The mean age at surgery was 66.4 ± 10.2 years. The mean time between implantation of the primary prosthesis and rupture was 7.0 ± 2.9 years. In six patients, the rupture was caused by trauma; in the others, it was secondary to previous surgery for treatment of knee stiffness (two cases) or infection (one case), and an arthroplasty revision was performed at the same time.

The allograft comprised the entire knee extensor apparatus, frozen at −80 °C, in accordance with current quality standards.1

In all cases, the surgery was performed using an anterior medial approach, over the previous incision. After identifying the patella and extensor apparatus, it was longitudinally divided, with total patellectomy and identification of the anterior tibial tuberosity. In it, a diamond-shaped bed was opened, so as to impact the donor graft into the recipient area. Fibrotic tissues and those of poor quality and viability of the quadricipital tendon were also excised. While the patient's recipient bed was being prepared, another team thawed the allograft and prepared its tibial tuberosity for placement on the patient's recipient bed. The final implantation of the graft began by inserting the tibial tuberosity of the graft on to the patient's tibial tuberosity bed; the graft was secured with screws or cerclage wiring, according to the patient's local condition. The final suture to the patient's quadricipital muscle was made in extension, under tension with nonabsorbable sutures (Fig. 1).

Postoperatively, the knees were immobilized with an articulated orthosis locked in extension for the first three weeks; weight-bearing was authorized with the support of Lofstrand crutches. Three weeks after surgery, the orthosis joint was unlocked and patients were encouraged to perform knee flexion and extension exercises. Six weeks after surgery, the orthosis was removed; patients were required to continue using Lofstrand crutches for another two weeks. At eight weeks, patients were encouraged to walk about without crutches and continue to perform joint mobility exercises.

Thromboembolic prophylaxis was conducted; oral antibiotic therapy (amoxicillin and clavulanic acid) was continued for a further two weeks after surgery.

Clinical and radiographic assessment2 (Fig. 2) were performed at six weeks, six months, one year, and yearly thereafter. In each evaluation, the Knee Society score and the functional knee score,6 validated for the Portuguese language,7 were used; active joint range of motion was measured with a goniometer.

The data included in the present study refer to the last evaluation as seen in the medical records.



Two patients who underwent the procedure died, at one and four years after the surgery, from causes unrelated to the procedure. In the three patients in whom arthroplasty revision was associated, complications were observed (infection in one case and suture dehiscence in the other two), requiring re-intervention with knee arthrodesis until the end of the first year. Thus, the study focused mainly on six cases, with a mean follow-up of 2.7 ± 1.9 years (14-1).

The mean Knee Society scores were 70 ± 8.5 (60-87) and 68 ± 7.5 (50-80) on functional evaluation; preoperatively, those values were 20 ± 3.5 (0-40) and 25 ± 7.5 (0-45), respectively.

Regarding active mobility, the mean lack of extension was 6 ± 0.5 (0-8). The mean active flexion was 90° ± 5.5° (80-100; Fig. 3). The mean range of motion was 82 ± 6.5 (90-100).

Overall survival was 44%, the main complications being observed during the first year after surgery (Fig. 4).



Patellar tendon rupture after total knee arthroplasty is a rare but highly taxing complication for the patient.2,3 Several treatment options are available, including the use of a complete knee extensor allograft, as described by Noronha et al.8 in isolated patellar tendon ruptures and by Emerson et al.9 in ruptures observed in patients who have undergone total knee arthroplasty. Chen et al.10 demonstrated that allograft integration is more time-consuming, but equally effective, and preserves the biomechanical properties. These data are in line with those described with the use of bone-tendon-bone allograft for anterior cruciate ligament reconstruction.11

The extensor apparatus allografts used in the present study were provided by the Bone Tissue Bank of the medical service, collected from donors with brain death or already deceased. The selection criteria followed the protocols set forth by Portuguese legislation and were in accordance with the quality standards of the Tissue Bank.12 The use of allograft is not free from risks or complications; despite being extremely low, an increased risk of transmission of diseases and infection from the donor to the host cannot be excluded.12 In all cases, frozen allografts were used as they reduce the risk of immunogenicity and do not compromise the biomechanical properties of the allograft.13,14

In the studies retrieved from the literature,5,9,12,15-20 the functional results are fair, with some improvement in the patients' quality of life. With the exception of the study by Nazarian,20 the number of patients is scarce. The final mobility observed in each series showed a range of motion of approximately 90°. It was also observed that patients presented an extension lag between 1.5°20 and 59°.5 The differences were related to the allograft fixation technique; the greatest deficits were observed in patients in whom the suture to the quadricipital tendon was made in flexion and with little tension.6 A significant complication rate was observed, ranging from 86%5 to 7%.12 Therefore, this is a high-risk option that should only be used as a last resort.

The findings of the present study are in line with several previously published studies. The surgical technique used, followed the recommendations by Burnett et al.5 The authors benefited from the knowledge of the literature, which indicates worse functional results when sutures were placed under low tension and in flexion.

Functional results, notably mobility, were fair, as evidenced by the range of motion and functional evaluation of the knee; nonetheless, they were certainly better than what would have been achieved by other treatments, as recently reported by Vaishya et al.21

The complications observed in this series (33%) were in agreement with those observed in the long-term follow-up study by Brown et al.22 The observed complications required arthrodesis in patients in whom it was necessary to simultaneously revise the prosthesis. The technique described by Vince and Bédard23 was used to impact the graft into the anterior tibial tuberosity. However, the poor results are due to complications inherent to arthroplasties, notably skin complications described in the literature.24 Contrary to what was advocated by Emerson et al.,9 the skin suture became quite tense postoperatively. This led to an early suture dehiscence, with subsequent skin necrosis, and finally to secondary graft infection. From the experience gained, the authors recommend an assessment of the patient's skin; when in doubt, working together with a plastic surgeon is recommended.

In the present series, the survival rate was 44.4%; while lower than expected, the result is justified by the three cases of complications previously discussed. After the first year of surgery, the patients were stable and able to perform their daily activities.

Morbidity is still high and the functional results are only fair; the procedure is more satisfactory to the surgeon than to the patient. These aspects should be clearly presented to the patient, who should also be aware of the inability to meet a high functional demand after the procedure.



Frozen allograft of the knee extensor apparatus is a good option in the treatment of patellar tendon rupture in patients who underwent total knee arthroplasty. However, this solution has high morbidity and the results are far from exceptional.

The solution should be well-studied; the local conditions, especially skin conditions, should be evaluated, and the limitations and possible complications must be explained clearly and succinctly to the patient.



Lynch AF, Rorabeck CH, Bourne RB. Extensor mechanism complications following total knee arthroplasty. J Arthroplasty. 1987;2(2):135-40.
Rand JA. Extensor mechanism complications after total knee arthroplasty. Instr Course Lect. 2005;54:241-50.
Schoderbek RJ, Brown TE, Mulhall KJ, Mounasamy V, Iorio R, Krackow KA, et al. Extensor mechanism disruption after total knee arthroplasty. Clin Orthop Relat Res. 2006;446:176-85.
Christen B, Baldini A, Becker R. Extensor apparatus insufficiencies. In: Hirschmann MT, editor. The unhappy total knee replacement. New York: Springer; 2015. p. 687–700.
Burnett RS, Berger RA, Paprosky WG, Della Valle CJ, Jacobs JJ, Rosenberg AG. Extensor mechanism allograft reconstruction after total knee arthroplasty. A comparison of two techniques. J Bone Joint Surg Am. 2004;86(12):2694-9.
Insall JN, Dorr LD, Scott RD, Scott WN. Rationale of the Knee Society clinical rating system. Clin Orthop Relat Res. 1989;(248):13-4.
Lebre F, Fonseca F. Como avaliar um doente com a escala IKS. Rev Port Ortop Traum. 2002;10(4):263-8.
Noronha JC, Silva C, Fonseca F, Leitão JC, Alegrete N. Utilidade do aparelho extensor de cadáver. Rev Port Ortop Traum. 1999;7(2):133-40.
Emerson RH, Head WC, Malinin TI. Extensor mechanism reconstruction with an allograft after total knee arthroplasty. Clin Orthop Relat Res. 1994;(303):79-85.
Chen G, Zhang H, Ma Q, Zhao J, Zhang Y, Fan Q, et al. Fresh-frozen complete extensor mechanism allograft versus autograft reconstruction in rabbits. Sci Rep. 2016;25(6):22106.
Fonseca F. Enxerto alógeno osso-tendão-osso nas ligamentoplastias do ligamento cruzado anterior [tese]. Coimbra: Universidade de Coimbra. Faculdade de Medicina; 1995. Available at:
Barrack RL, Stanley T, Allen Butler R. Treating extensor mechanism disruption after total knee arthroplasty. Clin Orthop Relat Res. 2003;(416):98-104.
Judas F, Teixeira L, Proença A. Coimbra University Hospitals' bone and tissue bank: twenty-two years of experience. Transplant Proc. 2005;37(6):2799-801.
Hu J, Qu J, Xu D, Zhou J, Lu H. Allograft versus autograft for anterior cruciate ligament reconstruction: an up-to-date meta-analysis of prospective studies. Int Orthop. 2013;37(2):311-20.
Llombart Blanco R, Valentí A, Díaz de Rada P, Mora G, Valentí JR. Reconstruction of the extensor mechanism with fresh-frozen tendon allograft in total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2014;22(11):2771-5.
Cadambi A, Engh GA. Use of a semitendinosus tendon autogenous graft for rupture of the patellar ligament after total knee arthroplasty. A report of seven cases. J Bone Joint Surg Am. 1992;74(7):974-9.
Crossett LS, Sinha RK, Sechriest VF, Rubash HE. Reconstruction of a ruptured patellar tendon with achilles tendon allograft following total knee arthroplasty. J Bone Joint Surg Am. 2002;84-A(8):1354-61.
Leopold SS, Greidanus N, Paprosky WG, Berger RA, Rosenberg AG. High rate of failure of allograft reconstruction of the extensor mechanism after total knee arthroplasty. J Bone Joint Surg Am. 1999;81(11):1574-9.
Bonnin M, Lustig S, Huten D. Extensor tendon ruptures after total knee arthroplasty. Orthop Traumatol Surg Res. 2016;102(1 suppl.):S21-31.
Nazarian DG, Booth RE. Extensor mechanism allografts in total knee arthroplasty. Clin Orthop Relat Res. 1999;(367):123-9.
Vaishya R, Agarwal AK, Vijay V. Extensor mechanism disruption after total knee arthroplasty: a case series and review of literature. Cureus. 2016;8(2):e479, 4.
Brown NM, Murray T, Sporer SM, Wetters N, Berger RA, Della Valle CJ. Extensor mechanism allograft reconstruction for extensor mechanism failure following total knee arthroplasty. J Bone Joint Surg Am. 2015;97(4):279-83, 18.
Vince KG, Bédard M. Extensor mechanism disruption after total knee arthroplasty. In: Scott WN, editor. Insall & Scott surgery of the knee. 5th ed. Philadelphia: Churchill Livingstone; 2011. p. 1389–410.
Fonseca F. Complicações cutâneas em artroplastias do joelho. Rev Port Ortop Traum. 2004;12(1):33-7.
O autor declara não haver conflitos de interesse.