Lumbar bone stress injuries and risk factors in adolescent cricket fast bowlers

Figures & data

Table 1. Details of the baseline and prospective lumbar bone stress injuries that occurred in adolescent fast bowlers.

Recorded	Descriptive	Category	Number of LBSI	LBSI/bowler* or LBSI/100 bowlers/year#
Baseline	Age (years)	14 15 16 17	3 1 3 1	0.19* 0.09* 0.43* 0.17*
	Maturation	Delayed Normal Advanced	1 6 1
	Lumbar level	L2 L4 L5 Multi-level	1 1 4 2
	Location	Superior articular process Pedicle Pars interarticularis Pedicle and pars interarticularis	1 1 7 2
	Side	Ipsilateral Contralateral Bilateral	1 6 2
	Severity	Bone stress Chronic bone stress Chronic stress fracture	5 2 2
Prospective	Age (years)	14 15 16 17 18	0 0 0 2 4	0 0 0 25# 80#
	Maturation	Delayed Normal	2 4
	Lumbar level	L4 L5 Multi-level	2 2 2
	Location	Pars interarticularis	8
	Side	Contralateral	8
	Severity	Bone stress Incomplete stress fracture	2 6

The side of the vertebra is respective to bowling arm. The number of injuries are reported, not the number of injured players. LBSI: lumbar bone stress injuries.

Table 2. Comparison of uninjured and prospectively injured fast bowlers.

		Injured group (95% CI) n = 6	Uninjured group (95% CI) n = 16	Mean difference between groups (95% CI)	T-test P value	Hedges’ g effect size
Height (cm)		184.8 (181.1 – 188.6)	180.9 (177.6 – 184.3)	3.9 (2.4 – 10.2)	0.215	0.587**
Weight (kg)		75.1 (71.1 – 79.0)	69.1 (63.7 – 74.5)	6.0 (3.8 – 15.8)	0.218	0.586**
Fat free mass (kg)		62.7 (58.0 – 67.3)	58.0 (53.7 – 62.2)	4.7 (3.3 – 12.7)	0.235	0.564**
Chronological age (years)		16.8 (16.2 – 17.5)	15.6 (15.1 – 16.0)	-1.3 (-2.1 – -0.4)	0.006	1.396***
Skeletal age (years)^†		15.9 (15.1 – 16.7)	15.6 (15.2 – 16.0)	-0.3 (-1.2 – 0.7)	0.278	0.274*
Skeletal maturity rating^†		-0.3 (-0.8 – 0.0)	0.0 (-0.3 – 0.3)	0.3 (-0.2 – 0.9)	0.363	0.611**
L3 CL BMD (g/cm^2)^†		1.625 (1.357 – 1.894)	1.419 (1.315 – 1.523)	-0.206 (-0.455 – 0.042)	0.178	0.812***
L4 CL BMD (g/cm^2)		1.667 (1.370 – 1.963)	1.432 (1.317 – 1.547)	-0.235 (-0.509 – 0.040)	0.090	0.849***
L3 vertebral area (cm^2)		17.65 (16.52 – 18.78)	16.64 (15.67 – 17.62)	-1.01 (-2.87 – 0.86)	0.273	0.519**
L4 vertebral area (cm^2)		19.08 (18.08 – 20.07)	18.29 (17.15 – 19.42)	-0.79 (-2.88 – 1.30)	0.439	0.377*
CL ankle dorsiflexion (cm)		9.3 (7.9 – 10.6)	11.2 (9.59 – 12.75)	1.92 (-1.01 – 4.85)	0.187	0.634**
CL ankle dorsiflexion (°)		54.7 (51.6 – 57.8)	51.6 (47.3 – 55.9)	-3.1 (-10.9 – 4.7)	0.421	0.380*
Sit and reach length (cm)^†		19.0 (14.0 – 24.1)	17.5 (14.7 – 20.4)	-1.5 (-7.5 – 4.6)	0.369	0.238*
Hip internal rotation (°)	CL^†	32.3 (25.7 – 39.0)	39.5 (36.3 – 42.7)	7.2 (0.1 – 14.3)	0.115	0.987***
	IL	33.3 (27.0 – 39.7)	36.9 (32.5 – 41.2)	3.5 (-5.2 – 12.2)	0.406	0.395*
Hip external rotation (°)	CL	34.2 (28.4 – 40.0)	33.5 (26.9 – 40.0)	-0.7 (-10.3 – 8.9)	0.879	0.056
	IL	31.0 (22.6 – 39.4)	33.7 (28.9 – 38.4)	2.7 (-7.3 – 12.6)	0.582	0.261*
Bent knee fall out (°)	CL	62.5 (58.3 – 66.7)	55.5 (49.4 – 61.6)	-7.0 (-18.1 – 4.2)	0.207	0.603**
	IL	60.2 (54.4 – 65.9)	55.5 (49.5 – 61.6)	-4.6 (-16.0 – 6.8)	0.405	0.393*
Straight leg raise (°)	CL	68.0 (65.1 – 70.9)	67.9 (64.3 – 71.4)	-0.1 (-6.7 – 6.4)	0.966	0.019
	IL	68.0 (64.7 – 71.3)	68.9 (65.8 – 72.1)	0.9 (-5.0 – 6.9)	0.746	0.151
Total balls bowled (n. balls)		1608 (1035 – 2181)	1237 (911 – 1563)	-371 (-1314 – 572)	0.397	0.526**
Bowling days per week (n. days)^†		2 (1 – 3)	2 (2 – 3)	-0 (-1 – 1)	1.000	0.092
Peak acute workload (n. balls)		229 (171 – 286)	165 (134 – 196)	-64 (-155 – 28)	0.150	0.942***
Peak medium workload (n. balls)		1214 (796 – 1631)	885 (677 – 1094)	-328 (-973 – 316)	0.279	0.700**

^† Mann-Whitney test. CL: contralateral; IL: ipsilateral; BMD: bone mineral density. P < 0.050 in bold. ***large effect size (g ≥ 0.80), **medium effect size (0.80 > g ≥ 0.50), * small effect size (0.50 > g ≥ 0.20).