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Histologic Evaluation of Tibial Attachment in 11-Year Double-Bundle ACL Reconstruction with Hamstring Tendons

A Case Report

Okazaki, Yuki MD, PhD1,2; Abe, Nobuhiro MD, PhD1,a; Makiyama, Kimihiko MD, PhD1; Furumatsu, Takayuki MD, PhD2; Miyazawa, Shinichi MD, PhD2; Ozaki, Toshifumi MD, PhD2

Author Information
doi: 10.2106/JBJS.CC.20.00509
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  • Disclosures

Abstract

Anterior cruciate ligament reconstruction (ACLR) using a tendon graft in a bone tunnel has become popular in the past 10 years1,2. Tendon-bone healing at the bone tunnel is a main concern when using a tendon graft for ACLR. The tendon graft and host bone tunnel are different tissue types, making tendon-bone incorporation complex and slow3, and it is important to stimulate biological healing between the graft and the bone tunnel. Several methods have been suggested to promote firm biological healing including the use of platelet-rich plasma, negative pressure, growth factors, stem cells, scaffolds, periosteal flaps, and mechanical loading3-8. Although tendon-bone healing after ACLR with a hamstring tendon graft has been reported in an animal study, to the best of our knowledge, there is no report on ACLR of the human tibia with a long-term follow-up. This report describes the histologic findings of a case of tendon-bone healing of the tibia 11 years after double-bundle ACLR (DBACLR) with hamstring tendons and to evaluate morphological regeneration in comparison with the native anatomical tibial attachment.

The patient was informed that data concerning the case would be submitted for publication, and she provided consent.

Case Report

A 49-year-old woman complained of left knee pain and instability. She had injured her left knee during gymnastics as a high-school student and had undergone lateral collateral ligament repair and bilateral subtotal meniscectomy 7 and 23 years after injury, respectively; ACLR was not performed in those times. On presentation, physical examination revealed signs of anterior cruciate ligament (ACL) rupture. Manual knee laxity tests, including the Lachman and anterior drawer tests, but not the McMurray test, were positive. From preoperative radiographs, the femorotibial angle and the Kellgren-Lawrence grade were 179° and 1, respectively (Figs. 1-A and 1-B). The anterior tibial translation measured using KT-2000 (MedMetric) was 10 mm, with side-to-side difference when the measurement was performed at maximal manual anterior force under general anesthesia. Standard arthroscopic examination showed cartilage degeneration (International Cartilage Research Society grade III) in the bilateral compartments. Moreover, DBACLR was performed with semitendinosus and gracilis tendon grafts. The anteromedial bundle (AMB) socket was created using a 6-mm-diameter drill through the tibial tunnel and the posterolateral bundle (PLB) socket with a 4.5-mm-diameter drill through the far anteromedial portal at 130° knee flexion. The tibial tunnel was created elliptically using an 8-mm-diameter drill to imitate the native orientation of ACL fibers. The grafts were fixed with a cortical suspension device (Endobutton, Smith and Nephew) at the femoral side and with a screw after system (Double Spike Plate; Meira) at the tibial side under an initial tension of 30/20 N for the AMB/PLB at 30° knee flexion.

Fig. 1
Fig. 1:
Radiographs of the knee. Figs. 1-A and 1-B Radiographs just before ACLR. Figs. 1-C and 1-D Radiographs just before TKA 11 years after ACLR. Figs. 1-E and 1-F T1-weighted and proton density-weighted magnetic resonance imaging just before TKA showing a well-matured grafted hamstring tendons. ACLR = anterior cruciate ligament reconstruction and TKA = total knee arthroplasty.

As the years progressed, osteoarthritic changes gradually deteriorated (Kellgren-Lawrence grade 3; Figs. 1-C and 1-D) and the range of motion was restricted to 0 to 115° although the reconstructed ACL was clearly identified (Figs. 1-E and 1-F) in magnetic resonance (MR) imaging and resulted in a negative Lachman test with a firm end point. Total knee arthroplasty was performed to relieve severe pain 11 years post-DBACLR. The proximal tibia was osteotomized using a System 6 sagittal saw (Stryker) (Figs. 2-A and 2-B). The obtained sample was fixed in a 10% neutral buffered formalin and decalcified in a 20% ethylenediaminetetraacetic acid solution (Figs. 2-C through 2-E). Longitudinal sections (6 μm thick) were sequentially assessed by hematoxylin-eosin staining, as previously described9, using light and polarized microscopies to examine the tendon-bone interface, tendon cell morphology, and attachment distribution (Figs. 3 and 4). Chondrogenic differentiation was evaluated by Safranin-O and toluidine blue metachromatic staining and confirmed by immunohistochemical analyses using antibodies against cartilage-specific type II collagen (COL2A1; Santa Cruz, sc-70 52658) and aggrecan (Santa Cruz; sc-33695) (Fig. 5).

Fig. 2
Fig. 2:
Macroscopic findings. Figs. 2-A and 2-B Superior findings of the cut tibia. Figs. 2-C and 2-D Inferior findings of the cut tibia. Each number from 1 to 4 is the number of cut slice. Fig. 2-E Medial findings of each slice. Each slice number correlates with the number in Figs. 2-B and 2-D. LTP = lateral tibial plateau, MTP = medial tibial plateau, med = medial, lat = lateral, and red elliptical circle = created bone tunnel in primary anterior cruciate ligament reconstruction.
Fig. 3
Fig. 3:
Histological findings of the tendon graft in the medial side of the bone tunnel (slice 2 in Fig. 2) with hematoxylin-eosin stain using routine light microscopy (Figs. 3-B, 3-D, 3-F, and 3-H) and polarized microscopy (Figs. 3-C, 3-E, 3-G, and 3-I). Fig. 3-A Gross appearance. No boundaries are identified between the anterior and posterior bundles. Figs. 3-B and 3-C Anteromedial side of the intraarticular exit showing Sharpey-like fibers connecting the tendon graft and lamellar bone. Figs. 3-D and 3-E Anteromedial side of the proximal aspect of the tunnel showing abundant Sharpey-like fibers connecting the tendon graft and the woven bone. Figs. 3-F and 3-G Posteromedial side of the intraarticular exit showing the chondral tendon insertion with well-aligned fibrocartilage indicating chondral metaplasia of the tendon graft. Figs. 3-H and 3-I Posteromedial side of the distal aspect of the tunnel showing no apparent Sharpey-like fibers connecting the tendon graft and lamellar bone (Fig. 3-A: ×20 magnification, Figs. 3-B through 3-I; ×200 magnification). BM = bone marrow, C = chondrocyte, L = lamellar bone, S = Sharpey-like fiber, and T = tendon graft.
Fig. 4
Fig. 4:
Histological findings of the tendon graft in the lateral side of the bone tunnel (slice 3 in Fig. 2) with hematoxylin-eosin stain using routine light microscopy (Figs. 4-B, 4-D, 4-F, and 4-H) and polarized microscopy (Figs. 4-C, 4-E, 4-G, and 4-I). Fig. 4-A Gross appearance. Lower magnification. Figs. 4-B and 4-C Posterolateral side of the intraarticular exit showing well-aligned chondrocytes indicating chondral metaplasia of the tendon graft as the formation of chondral insertion. Figs. 4-D and 4-E Posterolateral side of the proximal aspect of the tunnel showing abundant Sharpey-like fibers connecting the tendon graft and lamellar bone. Figs. 4-F and 4-G Posterolateral side of the distal aspect of the tunnel showing no apparent Sharpey-like fibers connecting the tendon graft and lamellar bone. Figs. 4-H and 4-I Anterolateral side of the intraarticular exit showing fatty metamorphosis of the surface of the tendon graft and Sharpey-like fibers connecting the tendon graft and lamellar bone (Fig. 3-A: ×20 magnification, Figs. 3-B through 3-I; ×200 magnification). BM = bone marrow, C = chondrocyte, L = lamellar bone, S = Sharpey-like fiber, and T = tendon graft.
Fig. 5
Fig. 5:
Histological findings of the tendon graft in the lateral side of the bone tunnel using light microscopy (the same area as Figs. 4-B and 4-C). Chondral metaplasia of the tendon graft as posterolateral side of the intraarticular exit was confirmed. Histology images (Fig. 5-A) Safranin-O, (Fig. 5-B) toluidine blue staining, and immunostaining using (Fig. 5-C) type II collagen antibody and (Fig. 5-D) aggrecan antibody (Figs. 5-A through 5-D: ×200 magnification). BM = bone marrow, C = chondrocyte, L = lamellar bone, and T = tendon graft.

At the medial side of the bone tunnel (Fig. 3-A), Sharpey-like fibers connected the tendon graft and lamellar bone anteriorly (Figs. 3-B through 3-E), although the distal aspect of the tunnel in which the distal end of the graft was located showed no apparent Sharpey-like fibers connecting the tendon graft and lamellar bone posteriorly (Figs. 3-H and 3-I). The intraarticular exit of the tunnel showed a transition zone of chondrocytes between the bone and the graft posteriorly (Figs. 3-F and 3-G). No clear boundary was noted between the anterior and posterior bundles (Fig. 3-A). At the lateral side of the bone tunnel (Fig. 4-A), the intraarticular exit showed well-aligned chondrocytes posteriorly (Figs. 4-B and 4-C), indicating chondral metaplasia that was detected by Safranin-O and toluidine blue staining and immunohistochemical analyses which confirmed the presence of type II collagen and aggrecan (Fig. 5). The proximal aspect of the tunnel located near the entrance of joint showed abundant Sharpey-like fibers connecting the tendon graft and lamellar bone posteriorly (Figs. 4-D and 4-E), whereas the distal aspect of the tunnel showed no apparent Sharpey-like fibers even posteriorly; however, fibroblastic proliferation was observed as connecting the tendon graft and lamellar bone (Figs 4-F and 4-G). In addition, the intraarticular exit showed fatty metamorphosis of the tendon graft anteriorly (Figs. 4-H and 4-I).

Discussion

Mimicking the anatomical tunnel position and original tension and stimulating biological healing between the graft and the bone tunnel are considered important to obtain firm tendon-bone healing with good clinical outcomes8. Considerable biomechanical7,10, biological4-6, histologic9,11-13, imaging14, and anatomical15,16 analyses of tendon-bone healing after ACLR exist. Although tendon-bone healing post-ACLR with a hamstring tendon graft has been reported in animal or human knees, to the best of our knowledge, this is the first report in the human tibia after a long-term follow-up.

In our reconstructed hamstring tendon graft, which was firmly attached to the bone against the anterior force and was mature under MR imaging evaluation, the tendon-bone healing at the tibial attachment was similar to the native transitional structure in the respective location. Although fatty morphosis was partially identified at the anterolateral side of the intraarticular aperture, the anterior side of the graft showed clear Sharpey-like fibers. The posterior side of the graft was attached to 3 different forms by depth from the intraarticular exit. The tendon graft-bone interface exhibited chondral metaplasia at the intraarticular exit, Sharpey-like fibers connection to the lamellar bone at the proximal aspect of the tunnel, and fibroblastic adherence at the distal aspect of the tunnel. Previous studies involving humans demonstrated various histologic findings regarding hamstring tendon graft anchorage in the bone tunnel14-17. Petersen et al. showed that the hamstring graft-bone tunnel interface resembled a fibrous insertion, which comprised 3 distinct histological zones: zone I (dense connective tissue of the tendon graft), zone II (woven bone; collagen fibers penetrate the woven bone from the dense connective tissue of the graft), and zone III (lamellar bone)14. In our case, this fibrous insertion was detected in the hamstring graft-bone interface at the distal aspect of the tunnel as previously reported concerning tendon-bone healing13,14 and caused by the unlikely load transfer between the graft and the bone.

Other reports described that an indirect insertion with collagen continuity resembling Sharpey's fibers, connecting the woven bone between the hamstring graft and the bone in a tibial tunnel, was achieved by direct contact with interference screw fixation11,15, and the press-fit matching the tunnel diameter corresponds to the graft16. In our case, this indirect insertion with Sharpey's fiber was shown at the anterolateral and posterior sides of the proximal aspect of the tunnel where the graft would be tensioned and forced against the tunnel wall during knee motion.

The chondral tendon remodeling, resembling the chondral enthesis, was shown at the posterior intraarticular exit of the tunnel. Petersen et al. found this type of graft-bone insertion at the intraarticular exit of the tibial tunnel only when using the patellar tendon, not the hamstring tendon14. We considered that the posterior side of the graft would be forced against the tunnel rim for a long duration and would result in tendon osseointegration to the bone. Araki et al. reported about the highly bending load of the hamstring grafts that the centroid of the tibial articular aperture in the AMB moved 72° posterolaterally, whereas the PLB moved 14° posterolaterally in a DBACLR study18. Moreover, the hamstring graft would be stretched to the boundary between the graft and the posterior intraarticular exit of the tunnel to induce chondral metaplasia.

This case showed histologic findings of a tendon-bone graft of the tibia 11 years post-DBACLR with hamstring tendons. Good tendon-bone healing and chondral metaplasia were identified even over 10 years post-DBACLR. Enthesial fibrocartilage is necessary to effectively dissipate stress concentration and compensate for various elastic moduli of the ligament and bone, which is similar to the structure of a native ACL17. One of the goals of ACLR is to reestablish the natural ligament to the bone complex to restore the physiological ligament function. In this case, the autologous hamstring tendons were anchored to mimic the enthesial tendon-bone junction of the original ACL, especially at the posterior exit of the tunnel.

Note: The authors acknowledge Dr. Aki Yoshida for her help in interpreting histological and immunohistochemical stains.

References

1. Bartlett RJ, Clatworthy MG, Nguyen TN. Graft selection in reconstruction of the anterior cruciate ligament. J Bone Joint Surg Br. 2001;83(5):625-34.
2. Lawhorn KW, Howell SM. Principles for using hamstring tendons for anterior cruciate ligament reconstruction. Clin Sports Med. 2007;26(4):567-85.
3. Sun Z, Wang X, Ling M, Wang W, Chang Y, Yang G, Dong X, Wu S, Wu X, Yang B, Chen M. Acceleration of tendon-bone healing of anterior cruciate ligament graft using intermittent negative pressure in rabbits. J Orthop Surg Res. 2017;12(1):60.
4. Gulotta LV, Kovacevic D, Ying L, Ehteshami JR, Montgomery S, Rodeo SA. Augmentation of tendon-to-bone healing with a magnesium-based bone adhesive. Am J Sports Med. 2008;36(7):1290-7.
5. Sahoo S, Toh SL, Goh JC. A bFGF-releasing silk/PLGA-based biohybrid scaffold for ligament/tendon tissue engineering using mesenchymal progenitor cells. Biomaterials. 2010;31(11):2990-8.
6. Li YG, Wei JN, Lu J, Wu XT, Teng GJ. Labeling and tracing of bone marrow mesenchymal stem cells for tendon-to-bone tunnel healing. Knee Surg Sports Traumatol Arthrosc. 2011;19(12):2153-8.
7. Hettrich CM, Gasinu S, Beamer BS, Stasiak M, Fox A, Birmingham P, Ying O, Deng XH, Rodeo SA. The effect of mechanical load on tendon-to-bone healing in a rat model. Am J Sports Med. 2014;42(5):1233-41.
8. Di Benedetto P, Di Benedetto E, Fiocchi A, Beltrame A, Causero A. Causes of failure of anterior cruciate ligament reconstruction and revision surgical strategies. Knee Surg Relat Res. 2016;28(4):319-24.
9. Okazaki Y, Furumatsu T, Maehara A, Miyazawa S, Kamatsuki Y, Hino T, Ozaki T. Histological alterations to the hamstring tendon caused by cleaning during autograft preparation. Muscles Ligaments Tendons J. 2019;9(2):217-24.
10. Fujii M, Sasaki Y, Araki D, Furumatsu T, Miyazawa S, Ozaki T, Linde-Rosen M, Smolinski P, Fu FH. Evaluation of the semitendinosus tendon graft shift in the bone tunnel: an experimental study. Knee Surg Sports Traumatol Arthrosc. 2016;24(9):2773-7.
11. Nebelung W, Becker R, Urbach D, Röpke M, Roessner A. Histological findings of tendon-bone healing following anterior cruciate ligament reconstruction with hamstring grafts. Arch Orthop Trauma Surg. 2003;123(4):158-63.
12. Tomita F, Yasuda K, Mikami S, Sakai T, Yamazaki S, Tohyama H. Comparisons of intraosseous graft healing between the doubled flexor tendon graft and the bone-patellar tendon-bone graft in anterior cruciate ligament reconstruction. Arthroscopy. 2001;17(5):461-76.
13. Rodeo SA, Arnoczky SP, Torzilli PA, Hidaka C, Warren RF. Tendon-healing in a bone tunnel. A biomechanical and histological study in the dog. J Bone Joint Surg Am. 1993;75(12):1795-803.
14. Petersen W, Laprell H. Insertion of autologous tendon grafts to the bone: a histological and immunohistochemical study of hamstring and patellar tendon grafts. Knee Surg Sports Traumatol Arthrosc. 2000;8(1):26-31.
15. Pinczewski LA, Clingeleffer AJ, Otto DD, Bonar SF, Corry IS. Integration of hamstring tendon graft with bone in reconstruction of the anterior cruciate ligament. Arthroscopy. 1997;13(5):641-3.
16. Eriksson K, Kindblom LG, Wredmark T. Semitendinosus tendon graft ingrowth in tibial tunnel following ACL reconstruction: a histological study of 2 patients with different types of early graft failure. Acta Orthop Scand. 2000;71(3):275-9.
17. Johnson LL. The outcome of a free autogenous semitendinosus tendon graft in human anterior cruciate reconstructive surgery: a histological study. Arthroscopy. 1993;9(2):131-42.
18. Araki D, Kuroda R, Matsumoto T, Nagamune K, Matsushita T, Hoshino Y, Oka S, Nishizawa Y, Kurosaka M. Three-dimensional analysis of bone tunnel changes after anatomic double-bundle anterior cruciate ligament reconstruction using multidetector-row computed tomography. Am J Sports Med. 2014;42(9):2234-41.
Keywords:

anterior cruciate ligament; reconstruction; tibial attachment; tendon-bone healing; hamstring

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