|Year : 2018 | Volume
| Issue : 2 | Page : 131-136
Bone tunnel enlargement in anterior cruciate ligament reconstruction done using hamstring tendon autografts: A prospective clinical and computed tomography-based evaluation
Anindya Debnath1, Rajeev Raman1, Paras Kumar Banka1, Hirak Debnath2
1 Department of Orthopaedics, Medical College Kolkata, Kolkata, West Bengal, India
2 Department of Orthopaedics, Agartala Government Medical College, Agartala, Tripura, India
|Date of Web Publication||22-Nov-2018|
Dr. Anindya Debnath
C/o- Haripada Debnath, Netaji Road, Thana Road (Near Regional Rubber Board Office), PO: Dharmanagar, Agartala - 799 250, Tripura
Source of Support: None, Conflict of Interest: None
Context: Enlargement of osseous tunnels following anterior cruciate ligament (ACL) reconstruction is a newer discovery. This phenomenon is particularly valuable in planning for revision ACL reconstruction. Aim: The purpose of this study was to evaluate prospectively the increase in size of the tibial and femoral bone tunnel following arthroscopic ACL reconstruction with quadrupled hamstring autograft and fixation with biodegradable interference screws. Materials and Methods: A prospective study was conducted on 10 patients who underwent arthroscopic ACL reconstruction with quadrupled hamstring autograft and fixation with biodegradable interference screws. Tunnel width was measured at postoperative 2 weeks and an average of 1-year follow-up (range: 10–13 months). Clinical evaluation was done as per the International Knee Documentation Committee form. Paired Student's t-test and linear regression were used for statistical analysis. Results: There was a mean 14% enlargement in the femoral tunnel (from 9 mm at postoperative 2 weeks to 10.3 mm at postoperative 1 year) and 18% enlargement in the tibial tunnel (from 10.4 mm at postoperative 2 weeks to 12.2 mm at the postoperative 1-year follow-up). Both of these were statistically significant (P = 0.005 for femoral tunnel enlargement and P = 0.008 for the enlargement of the tibial tunnel). No statistically significant association was noted between tunnel enlargement and clinical results. Conclusion: Compared to previous similar studies, less tunnel widening was observed in the present study. We come to a conclusion that less aggressive rehabilitation program and anatomical graft fixation technique can help achieve the goal of minimum tunnel enlargement after ACL reconstruction.
Keywords: Anterior cruciate ligament reconstruction, bone tunnel, computed tomography evaluation, osseous tunnel
|How to cite this article:|
Debnath A, Raman R, Banka PK, Debnath H. Bone tunnel enlargement in anterior cruciate ligament reconstruction done using hamstring tendon autografts: A prospective clinical and computed tomography-based evaluation. J Orthop Traumatol Rehabil 2018;10:131-6
|How to cite this URL:|
Debnath A, Raman R, Banka PK, Debnath H. Bone tunnel enlargement in anterior cruciate ligament reconstruction done using hamstring tendon autografts: A prospective clinical and computed tomography-based evaluation. J Orthop Traumatol Rehabil [serial online] 2018 [cited 2019 Jan 21];10:131-6. Available from: http://www.jotr.in/text.asp?2018/10/2/131/245991
| Introduction|| |
Tear of the anterior cruciate ligament (ACL) is a commonly encountered injury among young sportsmen. Furthermore, this occurs in various motor vehicle accidents. Surgical reconstruction of the ligament is a commonly done procedure in the young sufferers. Various techniques are there in practice. Among various complications of the procedure, tunnel widening has been reported in recent years irrespective of the techniques adopted.,,,,
Increase in bone tunnel size was reported when ACL was reconstructed with bone–patellar tendon (PT)–bone allograft (cystic changes noted by Jackson et al.), hamstrings, Achilles tendon allograft, or using prosthetic ligaments.
The etiology of the enlargement of bone tunnels following ACL reconstruction remains obscure. Earlier, it was suggested that bone tunnel enlargement is mainly the result of an immune response to allograft tissue. However, more recent studies give more importance to other biological as well as mechanical factors. Biological factors include foreign-body immune response against allografts, nonspecific inflammatory response (osteolysis around implants), cell necrosis due to toxic products in the tunnel (metal and ethylene oxide), and heat necrosis as a response to drilling. Mechanical factors that contribute to tunnel enlargement include stress deprivation of bone within the tunnel wall, graft-tunnel motion, improper placement of the tunnels, and aggressive rehabilitation. Graft-tunnel motion refers to longitudinal and transverse motion of the graft within the bone tunnel. This motion can occur with various graft types and fixation techniques. Aggressive rehabilitation programs subject the graft-bone interface to early stress before biological incorporation is complete and thus may contribute to tunnel enlargement.,, Younger age, male sex, and delay in ACL reconstruction since the injury may be potential risks for enlargement.
The purpose of this study was to evaluate prospectively the increase in size of the tibial and femoral bone tunnel following arthroscopic ACL reconstruction with quadrupled hamstring autograft and fixation with biodegradable interference screws.
| Materials and Methods|| |
Our prospective study included 13 patients (8 men and 5 women) with isolated ACL tear who were treated from December 2013 to May 2014. They were explained regarding the research proposal, and informed consent was sought. Noncompliance to give consent was accepted as an exclusion criterion. Ethical clearance was given by the Institutional Ethical Committee. They underwent arthroscopic ACL reconstruction with quadrupled hamstring autograft (semitendinosus and gracilis [STG]) using rigid fixation with biodegradable screws (ABSOLUTE™ Interference Screw of DePuy Mitek, Inc., Raynham, Massachusetts, USA). This was followed by a less aggressive postoperative rehabilitation program [Table 1]. The mean patient age at the time of surgery was 23.8 years (range: 19–31 years). The mode of ACL injury had been acute sports injury (football) in ten of them and motor vehicle accident in three patients.
Preoperative evaluation of knee function and stability was performed using the International Knee Documentation Committee (IKDC) forms. Furthermore, plain radiographs were taken to exclude any skeletal injury or preexisting bone pathology.
Postoperatively, long knee extension brace was applied in 5° of knee flexion before mobilizing the patient out of the operation theater. Isometric muscle strengthening exercises were started as soon as the patient was out of the anesthetic effect. From next day onward, toe touch crutch walking was encouraged and rehabilitation protocol was followed as described in [Table 1].
Computed tomography (CT) of the femoral and tibial tunnel was done 2 weeks after the surgery and at 1-year follow-up. All the examinations were performed using a multi-slice CT scanner (GE Bravio CT385 series, 16 slice) with postprocessing multislab reconstructions on the sagittal and coronal planes. MSCT scanning was performed from a level just above the most proximal point of the femoral tunnel to a level just below the outer hole of the tibial tunnel. The slice thickness was 3 mm, with retro-reconstruction made in all patients.
Transosseous tunnel diameter was measured according to the method suggested by Iorio et al.
Eight different levels were defined for taking measurements:
- F1 femoral tunnel at the notch, axial [Figure 1]
- F2 femoral tunnel in the middle point, axial [Figure 2]
- F3 femoral tunnel in the middle point, on coronal image reconstruction [Figure 3]
- F4 femoral tunnel in the middle point, on sagittal image reconstruction [Figure 4]
- T1 tibial tunnel, axial at plateau [Figure 5]
- T2 tibial tunnel, axial at middle point [Figure 6]
- T3 tibial tunnel, sagittal at plateau [Figure 7]
- T4 tibial tunnel, sagittal at middle point [Figure 8].
|Figure 3: F3, femoral tunnel in the middle point, on coronal image reconstruction (labeled as “1”)|
Click here to view
All diameters were calculated in millimeters.
Ten patients were reviewed after a mean period of 1 year (range: 10–13 months) with an accurate clinical examination and using IKDC forms. Three patients refused to undergo radiological evaluation and were excluded from the study. New CT scanning of the femoral and tibial tunnel was performed following the same criteria used in the immediate postoperative evaluation.
Statistical analysis of all data was performed using Student's t-test and linear regression analysis.
| Results|| |
None of the ten patients suffered any complication and the recovery was smooth. All of them attained full range of motion by the end of the first 6 postoperative weeks. Preoperatively, six patients (60%) were graded C and remaining four (40%) were graded D as per the IKDC scoring system. Postoperatively, eight (80%) of them progressed to IKDC Grade A, and two (20%) patients were documented IKDC Grade B.
Two-week postoperative average femoral tunnel diameter was 9 mm and average tibial tunnel diameter was 10.4 mm. At 1-year follow-up, average femoral tunnel diameter was 10.3 mm and average tibial tunnel diameter was 12.2 mm. This increase in the diameter was found to be statistically significant (P = 0.005 and 0.008 for femoral and tibial tunnels, respectively). The comparison of individual parameters at 2 weeks and at 1 year has been showed in [Figure 9]. No association was noted between tunnel enlargement and clinical grading.
|Figure 9: Comparison between 2-week postoperative and 1-year postoperative measurements|
Click here to view
| Discussion|| |
Enlargement of the osseous tunnel after reconstruction of ACL has been a concern over past few years. Although it does not appear to affect the clinical outcome in the first 2 postoperative years,, long-term outcome of this phenomenon is not yet known and tunnel expansion may be clinically significant in revision surgery since the enlarged tunnels may complicate graft placement and fixation.
Buelow et al. compared the effect of extracortical suspension fixation with anatomical fixation using interference screws on the tunnel enlargement. They found that insertion of large interference screws not only compresses the graft in the bone tunnel but also significantly enlarges the bone tunnel itself. This is followed by a reduced further enlargement at 6 months and then stabilization of the tunnel. Tunnel enlargement has also been reported with extracortical fixation technique by them. In accordance with this study, follow-up evaluation of tunnel was done at 1-year follow-up in the present study.
Tunnel enlargement does get affected by the fixation used. Sabat et al. compared tunnel enlargement in patients undergoing ACL reconstruction with quadrupled hamstring graft by the use of either EndoButton or Transfix on the femoral side with a bioabsorbable interference screw in the tibial tunnel using CT scan. They observed that femoral tunnel widening was significantly less in the Transfix group compared with the EndoButton group. Mascarenhas et al. in a systemic review of meta-analysis demonstrated that clinical and functional outcomes were similar with metallic interference screws and bioabsorbable interference screws. However, prolonged knee effusion, femoral tunnel widening, and screw breakage were more common with bioabsorbable interference screw use. Cheung et al. found that femoral tunnel widening was greater in femoral cross pin fixation in contrast to bioabsorbable screw fixation augmented with Endopearl. They explained this finding with the windshield-wiper and bungee-cord effects. In their 5-year follow-up, they noted the tunnel widening to occur in the first 2 postoperative years which remained static thereafter.
Various theories are put forward to explain the etiopathogenesis as well as to suggest possible measures for preventing bone tunnel enlargement. In a review article, Hoher et al. explained the pathogenesis with the “bungee effect.” It is the longitudinal graft motion of a STG tendon-EndoButton reconstruction. Furthermore, various studies showed that early motion during rehabilitation increases the amount of tibial tunnel enlargement after ACL replacement with hamstring autograft.,
Greater enlargement in tunnel width was noted with hamstring graft as compared to bone PT bone graft. L'Insalata et al. argued for a mechanical cause due to fixation points of the hamstring graft being a greater distance from the articular surface than the fixation points of the PT graft that creates a potentially larger force moment during graft motion within the tunnel (the “windshield-wiper effect”). Clatworthy et al. found no enlargement in either tunnel of the PT group despite the use of suspensory fixation. Marked enlargement was, however, observed in the hamstring group with the same method of femoral fixation. Webster et al. proposed that the bone block used in PT autografts acts effectively as a bone graft and releases osteoinductive bone morphogenic protein into the bone tunnel and thus reduces postoperative tunnel widening.
Segawa et al. concluded that the main factors associated with tunnel enlargement were the locations and angles of the tunnels. Tunnel malposition causes change in the tension of the graft leading to enhanced windshield-wiper motion of the graft. An acute femoral tunnel angle may increase the mechanical stress on the anterior margin of the femoral tunnel. Thus, it is desirable that the tunnel placement is as anatomical as possible in order to control tunnel widening.
Zysk et al. observed an association between tibial bone tunnel enlargement and elevated synovial fluid concentrations of interleukin-6, tumor necrosis factor-α, and nitric oxide 7 days after ACL surgery. Based on this observation, they suggested the potential involvement of these biological mediators in the pathogenesis of bone tunnel enlargement. However, no significant difference was there between the elevations in their synovial fluid concentration after ACL reconstruction with hamstring or PT graft.
Marchant et al. demonstrated that CT is the most reliable imaging modality for the evaluation of ACL bone tunnels when compared to magnetic resonance imaging and plain radiographs. Measuring bone tunnels by plain radiographs can result in underestimating the real diameter of tunnel enlargement., Therefore, MSCT images were used to measure tunnel width in the present study.
Jansson et al. evaluated tunnel enlargement on anteroposterior (AP)-view radiography. They noted an average femoral and tibial tunnel enlargement of 33% and 23%, respectively. Hamstring graft was used for ACL reconstruction along with endobutton fixation in all of these patients.
Cheung et al. studied the effect of bioabsorbable interference screws on the enlargement of tunnel following ACL reconstruction with quadrupled hamstring graft. They used plain radiographs for measurement. At the 2-year follow-up, they observed overall. 23% femoral tunnel enlargement in the bioabsorbable screw group. The enlargement remained same at the 5-year follow-up (23%).
Jagodzinski et al. reported 121.9% ± 9.0% bone tunnel enlargement in the AP plane and 121.5% ± 10.1% in the coronal plane in their subset of patients whose ACL reconstruction was done with hamstring tendon graft and fixed with biodegradable interference screws. These measurements were done on CT scan images.
The results of the present study demonstrate 14% enlargement in the femoral tunnel and 18% enlargement in the tibial tunnel following ACL reconstruction using hamstring tendon autografts and graft fixation using biodegradable interference screws. This is lower than the previous studies, and this variation could probably be explained by following factors: (1) a less aggressive rehabilitation program was followed in this study. (2) Our follow-up was of 1 year only. Tunnel enlargement is likely to continue for a longer duration. (3) Anatomical graft placement was used in this study instead of conventional transtibial technique which had been more prone for tunnel widening. (4) Our sample size was small. For a better representation of the general population, further study with a larger sample size is needed.
As with many other authors,,,,,, no significant association between tunnel enlargement and clinical results was found in this study. However, like most of the studies done so far, this is only a short-term evaluation of the clinical effects of tunnel enlargement. Further studies and longer follow-up should be done to monitor the pattern and magnitude of tunnel enlargement, its effect on clinical outcome, if any, and the role of the definitive biological fixation of the graft in causation of the tunnel enlargement. Moreover, enlarged tunnels have the potential to cause difficulty with graft positioning and fixation in revision ACL surgery, eventually demanding a two-stage revision surgical procedure, increasing the morbidity and financial burden. Therefore, enlargement of the bone tunnels should be prevented, as far as possible.
| Conclusion|| |
Enlargement of osseous tunnels following ACL reconstruction is seen with hamstring graft fixed with biodegradable interference screws. In our study, there was less enlargement of the tunnel as compared to previous similar studies. We conclude that a less aggressive rehabilitation program and an anatomical graft fixation technique can yield a better result in achieving the goal of minimum tunnel enlargement after ACL reconstruction.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]