In vivo bone tunnel remodeling in symptomatic patients after ACL reconstruction: a retrospective comparison of articular and extra-articular fixation

Abstract

Background: there is only a paucity of studies dealing with bone remodeling within the tunnels after anterior cruciate ligament (ACL) reconstruction. The objective of this study was to evaluate the influence of tendon graft type and surgical fixation technique on bone tunnel remodeling in patients with symptomatic knees after ACL reconstruction. Methods: in a retrospective study 99mTc-HDP bone tracer uptake (BTU) in SPECT/CT of 57 knees with symptoms of pain and/or instability after ACL reconstruction was investigated. All 57 knees were subdivided according their anatomy (femur and tibia), fixation (articular versus extraarticular fixation) and graft types into eight groups: femoral-articular versus extra-articular fixation using bone-patellar tendon-bone (BPTB) and hamstring autografts; tibial-articular versus extra-articular fixation using patellar tendon and hamstring autografts; BTU grading for each area of the localisation scheme were recorded. Tunnel diameter and length was measured in the CT scans. Results: BTU was higher for the articular fixation in the femur and for the extra-articular fixation in the tibial tunnel. Patellar tendon graft fixation showed a significantly higher BTU in the superior-lateral and posterior-central area of the tibia, meaning the areas of the tibial tunnel near the entrance into the joint. Tunnel enlargement correlated significantly with increased BTU (p<0.05). Conclusion: assessment of in vivo bone tunnel remodelling in symptomatic patients after ACL reconstruction revealed different patterns of BTU with regards to graft and fixation method.

Good clinical results but moderate osseointegration and defect filling of a cell-free multi-layered nano-composite scaffold for treatment of osteochondral lesions of the knee

“…In the last decades, single photon emission computerised tomography/computerised tomography (SPECT/CT), which as a three‐dimensional hybrid imaging modality consists of a 3D bone scan and a conventional CT, has been increasingly used in patients with painful knees [25–28, 30–34, 49, 55, 56]. In particular, its ability to visualise the in vivo bone loading and to correlate such findings to biomechanical considerations has been highlighted [25, 32, 33, 47, 49, 50]. In contrast to MRI, SPECT/CT is able to provide information on alignment, structural pathologies, osseous physiology and metabolism together [12, 30].…”

Increased bone tracer uptake in symptomatic patients with ACL graft insufficiency: a correlation of MRI and SPECT/CT findings

“…after athletic activity [5, 30, 33]. BTU in SPECT/CT is also rather unspecific and can be found in the same conditions described above [20, 25, 26, 28, 35, 38, 39]. However, as the bone tracer used in SPECT/CT is directed towards active osteoblasts, it reflects an increased in vivo joint loading and also bone remodelling after ACL surgery [9, 13, 22].…”

“…In the last decades, single‐photon emission computerised tomography/computerised tomography (SPECT/CT), which is a three‐dimensional hybrid imaging modality consisting of a 3D bone scan (SPECT) and a conventional CT, has been increasingly used in patients with painful knees [20–27, 38, 43]. In particular, its ability to visualise the in vivo bone loading and correlate such findings with biomechanical considerations has been highlighted [20, 25, 26, 35, 38, 39]. In contrast to MRI, SPECT/CT is able to provide information on alignment, structural pathologies, osseous physiology and metabolism together [7, 23].…”

PET/MRI reveals ongoing metabolic activity in ACL grafts one year post-ACL reconstruction

“…Another imaging modality, SPECT/CT (Single‐photon emission computed tomography/computed tomography), has previously been used with diphosphonate bone tracers to evaluate changes in biomechanical loading and the subchondral bone plate [12]. Higher amounts of this bone tracer uptake has been shown to be significantly related to a higher degree of osteoarthritis in knees post‐ ACL reconstruction [14]. While this imaging modality serves to measure additional parameters (in vivo joint loading, bone tunnel remodeling and graft incorporation), interpretation is required to differentiate between an inflammatory response versus altered in vivo loading or both [13].…”