Abstract
Background:
Quadriceps tendon autograft represents an increasingly popular graft option for ACL reconstruction (ACLR). However, there is a paucity of literature regarding the early post-operative effects of this graft technique on functional recovery, particularly in adolescents.
Purpose/Hypothesis:
To quantify post-operative strength, dynamic balance, and functional hop test performance in adolescents 6 months following ACLR with a quadriceps tendon autograft (ACLR-Q) and compare to an adolescent control group who underwent ACLR with hamstring autograft (ACLR-HS).
Methods:
Patients 12-19 years-old who underwent primary ACLR-Q from 2017-2019 by a single surgeon at a pediatric tertiary care hospital and performed return to sports (RTS) assessments between 5-9 months post-operatively were included. Exclusion criteria were prior ipsilateral or contralateral ACLR and concomitant procedures other than meniscal repair or meniscectomy. RTS tests included manual muscle testing of strength (hamstring, quadriceps, hip abductor), dynamic-Y-balance, and functional hop tests (single-hop, triple-hop, crossover, 6-meter timed hop). Limb Symmetry Index (LSI) was calculated for all measures and each was compared with an ACLR-HS control group using T-tests. One-way between-group multivariate analysis of covariance (MANCOVA) was utilized to control for any baseline differences.
Results:
There were no significant differences in age, BMI, sex, or rates of meniscal procedures between cohorts (Table 1). The small difference in time of RTS testing was controlled by MANCOVA model. ACLR-Q patients demonstrated a significantly smaller hamstring strength deficit (-3.6%) than the ACLR-HS group (-35.8%, p<0.001, Table 2). The ACLR-Q group showed a significantly greater deficit in quadriceps strength (-11.9% vs. 0.9%, p<0.001). Hamstring-to-quadriceps strength ratios (HS:Q) were lower in the ACLR-HS (operative limb: 0.34 +/- 0.13, non-operative limb: 0.52 +/- 0.01) than the ACLR-Q group (operative limb: 0.61 +/- 0.16, non-operative limb: 0.56 +/- 0.12). Deficits in anterior reach, composite Y-balance score, cross-over hop, timed hop, and single hop were significantly greater in the ACLR-Q group. The deficit in 6-meter timed hop was significantly greater in the ACLR-HS group.
Conclusion:
Quadriceps strength deficits were greater in adolescents undergoing ACLR-Q (LSI of approximately -12%), while hamstring strength deficits were greater in adolescents undergoing ACLR-HS (LSI of approximately -33%). Hamstring-to-quad ratios were greater in the ACLR-Q patients’ operative knees than their nonoperative knees, while they were significantly lower in the ACLR-HS patients’ operative knee than their nonoperative knees. Hop testing performance was mixed between the 2 graft cohorts. The degree to which these performance metrics influence eventual athletic performance and graft-retear remains a critical area of continued investigation.
Patient demographics, rate of meniscal repair or meniscectomy at time of ACLR, and time from surgery to post-operative return to sport testing
| Quadriceps |
Hamstring |
p-value | |
|---|---|---|---|
| Demographics at time of surgery: | |||
| Age (years) | 16.2 ± 1.9 | 16.0 ± 1.6 | 0.410 |
| Height (cm) | 169.6 ± 9.5 | 168.0 ± 9.6 | 0.262 |
| Weight (kg) | 69.8 ± 16.1 | 65.9 ± 12.4 | 0.083 |
| BMI | 24.2 ± 4.6 | 23.3 ± 3.6 | 0.163 |
| Male | 40% | 38% | 0.764 |
|
|
29% | 25% | 0.476 |
|
|
20% | 18% | 0.662 |
|
|
6.39 ± 0.86 | 6.03± 0.50 | 0.002* |
Values are mean ±SD
*p < 0.05
Strength, balance, and hop testing 6 months following ACLR in two graft types
|
|
Quadriceps |
Hamstring |
p-value |
|---|---|---|---|
| Quadriceps Strength: | |||
| Non-operative limb | 273.0 ± 79.6 (251.6, 294.6) | 288.3 ± 78.1 (281.5, 295.0) | |
| ACLR limb | 238.8 ± 73.9 (218.8, 258.8) | 283.9 ± 80.4 (277.0, 290.8) | |
| LSI Deficit (%) | -11.9 (-15.6, -8.1) | -0.9 (-2.1, +0.4) | 0.000* |
| Hamstrings Strength: | |||
| Non-operative limb | 148.1 ± 38.3 (137.7, 158.4) | 146.1 ± 38.3 (142.8, 149.4) | |
| ACLR limb | 141.3 ± 39.5 (130.6, 152.0) | 93.3 ± 36.3 (90.2, 96.4) | |
| LSI Deficit (%) | -3.9 (-9.1, +1.4) | -35.8 (-37.6, -34.1) | 0.000* |
| Hamstring:Quadriceps ratio: | |||
| Non-operative limb | 0.56 ± 0.12 | 0.52 ± 0.01 | |
| ACLR limb | 0.61 ± 0.16 | 0.34 ± 0.13 | |
| Hip abductor Strength: | |||
| Non-operative limb | 122.2 ± 33.3 (113.2, 131.2) | 122.8 ± 47.3 (118.8, 126.9) | |
| ACLR limb | 118.9 ± 29.7 (110.9, 127.0) | 126.4 ± 48.0 (122.3, 130.6) | |
| LSI Deficit (%) | -1.4 (-6.5, +3.7) | +5.3 (+3.6, +7.0) | 0.015* |
| Anterior Reach: | |||
| Non-operative limb (cm) | 64.1 ± 8.2 (61.9, 66.3) | 60.4 ± 7.0 (59.8, 61.0) | |
| ACLR limb (cm) | 59.7 ± 6.4 (58.0, 61.5) | 58.7 ± 6.8 (58.2, 59.3) | |
| LSI Deficit (%) | -6.2 (-8.5, -3.8) | -2.5 (-3.3, -1.6) | 0.004* |
| Posteromedial Reach: | |||
| Non-operative limb (cm) | 98.9 ± 10.0 (96.2, 101.6) | 96.9 ± 10.4 (96.0, 97.8) | |
| ACLR limb (cm) | 96.8 ± 9.4 (94.5, 99.5) | 95.9 ± 11.6 (94.9, 96.9) | |
| LSI Deficit (%) | -2.1 (-4.1, -0.1) | -0.3 (-1.1, +0.4) | 0.106 |
| Posterolateral Reach: | |||
| Non-operative limb (cm) | 94.3 ± 12.5 (90.9, 97.7) | 93.0 ± 10.0 (92.2, 93.9) | |
| ACLR limb (cm) | 92.7 ± 11.0 (89.6, 95.6) | 92.4 ± 10.5 (91.5, 93.4) | |
| LSI Deficit (%) | -1.8 (-3.8, +0.2) | -0.2 (-1.0, +0.5) | 0.152 |
| Composite Score: | |||
| Non-operative limb (cm) | 96.6 ± 11.0 (93.7, 99.6) | 96.0 ± 7.8 (95.3, 96.8) | |
| ACLR limb (cm) | 93.3 ± 7.9 (91.2, 95.5) | 95.1 ± 8.3 (94.3, 95.9) | |
| LSI Deficit (%) | -3.2 (-4.6, -1.7) | -0.9 (-1.5, -0.4) | 0.006* |
| Single Hop: | |||
| Non-operative limb (m) | 1.10 ± 0.33 (1.00, 1.20) | 1.15 ± 0.26 (1.13, 1.18) | |
| ACLR limb (m) | 0.94 ± 0.32 (0.84, 1.03) | 1.07 ± 0.27 (1.04, 1.10) | |
| LSI Deficit (%) | -12.1 (-16.0, -8.1) | -6.8 (-8.3, -5.4) | 0.017* |
| Triple Hops: | |||
| Non-operative limb (m) | 3.70 ± 0.94 (3.40, 4.00) | 3.90 ± 0.78 (3.81, 3.98) | |
| ACLR limb (m) | 3.37 ± 0.90 (3.08, 3.66) | 2.95 ± 0.93 (2.85, 3.05) | |
| LSI Deficit (%) | -9.0 (-16.7, -1.3) | -22.3 (-25.1, -19.4) | 0.002* |
| Cross-over Hops: | |||
| Non-operative limb (m) | 3.26 ± 0.94 (2.95, 3.57) | 3.38 ± 0.82 (3.28, 3.47) | |
| ACLR limb (m) | 2.91 ± 0.79 (2.65, 3.18) | 3.18 ± 0.80 (3.09, 3.27) | |
| LSI Deficit (%) | -9.8 (-13.5, -6.2) | -5.4 (-6.7, -4.0) | 0.026* |
| 6 meter Timed Hop: | |||
| Non-operative limb (s) | 2.48 ± 0.64 (2.28, 2.69) | 2.33 ± 0.48 (2.27, 2.38) | |
| ACLR limb (s) | 2.64 ± 0.76 (2.39, 2.88) | 2.43 ± 0.53 (2.37, 2.49) | |
| LSI Deficit (%) | -5.7 (-2.4, 9.0) | -3.5 (-4.7, -2.3) | 0.000* |
LSI = Limb Symmetry Index
Values are mean ± standard deviation with 95% confidence interval.
*p < 0.05