Abstract
Purpose:
The aim of this study was to evaluate the influence of surgical experience of an orthopaedic surgeon on femoral and tibial tunnel placement during anterior cruciate ligament (ACL) reconstruction, and the effect of tunnel angle on patient self-report outcomes.
Methods:
We retrospectively reviewed 115 consecutive ACL reconstruction surgeries by a single fellowship-trained orthopaedic surgeon over his first 5 years in practice. 70 patients with hamstring (HS) and 44 patients with bone-patellar tendon-bone (BTB) autografts were included, all epiphyseal approaches, graft hybrids or allografts were excluded. Posterior distal femoral angle (PDFA), femoral and tibial tunnel angulation were measured on AP and lateral radiographs by 2 independent raters with high inter-rater reliability (ICC >0.8 for all measures). Tunnel angulation was compared to recently reported ideal femoral angle of 33.5°±1.8 or ideal tibial angle of 62.5°±5 (Luthringer et al, 2016). Complications and self-report outcomes - pediIKDC, Tegner-Lysholm and KOOSChild - were recorded, as well as demographics, injury and surgery characteristics (e.g. concurrent meniscal repairs, chondroplasty, tourniquet time). Average follow-up was 1.14 years. Continuous variables were analyzed using unpaired t-test, Wilcoxon rank sum test and Spearman correlation. Categorical variables were analyzed using Fisher’s exact test.
Results:
ACL reconstruction was performed at an average age of 16.7 years (range, 11.8 to 20.4 years), 59% males. Figure 1 shows tunnel angles over case groups of N=15. For HS autografts, femoral tunnel angle and tibial tunnel angle improved toward the ideal angle after 15 cases (ANOVA, p=0.020 and p=0.031, respectively). For BTB autografts, femoral tunnel angle and tibial tunnel angle did not demonstrate a significant change over cases (Figure 1).
The tibial tunnel angle in HS cases showed a negative weak correlation with the selected outcome scores at 6 months and 1 year after ACL reconstruction, whereas the tibial tunnel angle in BTB cases showed a weak positive correlation with KOOSChild pain scores 6 months after initial surgery (Table 1). For either graft type, femoral tunnel angle was not correlated with any outcome measure. Overall, self-report outcome scores were similar between patients with ideal and non-ideal tunnel angles (data not shown).
Of the 70 patients with HS autografts, 5 (7%) required a secondary surgery: 2 revisions for graft tear, 1 revision for a non-functional graft, 1 for arthrofibrosis and 1 for a prominent tibial screw. PDFA, femoral and tibial tunnel angle were similar between patients needing secondary surgery and those who did not (Table 2). Patients needing revision surgery had significantly lower Tegner-Lysholm and KOOSChild Pain scores at 6 months after the initial ACL reconstruction.
Of the 44 BTB patients, 3 (6.8%) had complications: 2 patients developed arthrofibrosis and subsequently underwent surgery, and 1 patient experienced neuropathy. In these patients, the PDFA was significantly higher, the femoral tunnel angle significantly lower and tibial tunnel angle similar compared to those without a complication (Table 2).
Demographic factors, injury and surgical parameters (concurrent meniscal repairs, chondroplasty, tourniquet time, aso) were similar between HS patients with or without additional surgery and between BTB patients with and without complications.
Conclusion/Significance:
Femoral and tibial tunnel angle improved towards the reported ideal angle after 15 cases for HS autografts. PDFA, femoral and tibial tunnel angle were not associated with surgical complications in HS patients. For BTB autografts, no significant changes were seen in tunnel placement with surgical experience. Patients experiencing complications after BTB autografts had a low femoral tunnel angle and high PDFA.
Overall, tibial tunnel angle, but not femoral tunnel angle, correlated with outcome scores of patients with BTB and HS autografts.
Femoral and tibial tunnel angles
Relationship between tunnel angles and patient self-report scores
| Spearman correlation | HS autograft | BTB autograft | |||
|---|---|---|---|---|---|
| Outcomes @ 6 months | Fem. Tunnel angle | Tibial Tunnel angle | Fem. Tunnel angle | Tibial Tunnel angle | |
| PediIKDC | 0.266 (ns) | -0.109 (ns) | -0.060 (ns) | -0.037 (ns) | |
| Tegner -Lysholm | 0.161 (ns) | -0.426 ( |
0.114 (ns) | 0.141 (ns) | |
| KOOSChild Pain | -0.237 (ns) | -0.408 (0.059) | 0.124 (ns) | 0.405 ( |
|
| KOOSChild Symptom | 0.088 (ns) | -0.463 ( |
0.083 (ns) | 0.146 (ns) | |
| KOOSChild ADL | -0.134 (ns) | -0.377 (0.084) | -0.135 (ns) | 0.003 (ns) | |
| KOOSChild Sport | 0.267 (ns) | -0.385 (0.085) | -0.209 (ns) | 0.216 (ns) | |
| KOOSChild QOL | -0.036 (ns) | -0.300 (ns) | 0.035 (ns) | 0.320 (ns) | |
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| PediIKDC | 0.026 (ns) | -0.461 ( |
0.106 (ns) | -0.342 (ns) | |
| Tegner -Lysholm | 0.032 (ns) | -0.454 ( |
0.153 (ns) | -0.126 (ns) | |
| KOOSChild Pain | 0.099 (ns) | -0.410 (0.073) | 0.234 (ns) | -0.199 (ns) | |
| KOOSChild Symptom | 0.034 (ns) | -0.430 (0.058) | 0.294 (ns) | 0.120 (ns) | |
| KOOSChild ADL | 0.076 (ns) | -0.470 ( |
-0.322 (ns) | -0.037 (ns) | |
| KOOSChild Sport | 0.137 (ns) | -0.644 ( |
0.118 (ns) | -0.164 (ns) | |
| KOOSChild QOL | -0.016 (ns) | -0.520 ( |
0.268 (ns) | -0.058 (ns) | |
Indicated is the Spearman correlation coefficient (p-value) ns=not statistically significant different, p>0.05
Comparison of radiographic measures between patients with and without complications
| HS autograft | No additional surgery | Additional surgery | p-value |
|---|---|---|---|
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34.6 ± 6.7 | 33.6 ± 4.0 | 0.727 |
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64.3 ± 7.3 | 67.7 ± 6.8 | 0.433 |
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87.5 ± 3.5 | 85.3 ± 5.4 | 0.123 |
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Mean ± SD indicated