Importance of computed tomography in posterior malleolar fractures: Added information to preoperative X-ray studies

Table 1 Demographic and lesion characteristics, n = 81

Characteristic	Subcategory	n (%)
Agea		39.48 (± 13.59)
Sex	Male	44 (54.32)
	Female	37 (45.67)
Diagnosis	Fracture	42 (51.85)
	Fracture + dislocation	39 (48.14)
AO/OTA 44	A	1 (1.23)
	B	51 (62.96)
	C	29 (35.80)
Haraguchi	1	29 (35.80)
	2	33 (40.74)
	3	19 (23.45)
Intermediate fragment	Yes	22 (27.16)
	No	59 (72.83)

^aMean (standard deviation). AO/OTA: AO Foundation/Orthopedic Trauma Association.

Table 2 Interobserver reliability of posterior malleolus size measurements

	Examiner X	Examiner Y	Pearson’s	P value
X-ray measurement
Absolute size of the tibia	5.28 (± 0.83)	5.09 (± 0.82)	0.88	< 0.001
Absolute size of the PM	1.43 (± 0.75)	1.32 (± 0.69)	0.92	< 0.001
MP size (PMXR)a	21.15 (± 10.20)	20.46 (± 9.66)	0.93	< 0.001
Mean PM sizea	20.81 (± 9.70)		-	-
CT measurement
Absolute size of the tibia	3.23 (± 0.65)	3.13 (± 0.62)	0.95	< 0.001
Absolute size of the PM	0.97 (± 0.38)	0.88 (± 0.37)	0.89	< 0.001
PM size (SAGCT)	23.45 (± 9.51)	22.39 (± 9.96)	0.94	< 0.001
Mean PM size	22.92 (± 9.60)
Interobserver agreement
PM < 25% in X-ray images	56	58	0.88	< 0.001
PM ≥ 25% in X-ray imagesb	25	23
PM < 25% in CTb	51	56	0.76	< 0.001
PM ≥ 25% in CTb	30	25

^aPercentage.

^bCases (absolute frequency). CT: Computed tomography; PM: Posterior malleolus; PMXR: Profile X-ray images of the posterior malleolus; SAGCT: Sagittal computed tomography images of the posterior malleolus.

Table 3 Analysis of the articular surface of the ankle affected by the posterior malleolar fracture in axial computed tomography slices

Grouping according to PMXR < 25% and ≥ 25% (cases)	All cases	Group A, < 25%	Group B, ≥ 25%	P value
	14.57% (81) (± 9.84)	10.13% (56) (± 6.71)	24.52% (25) (± 8.40)	< 0.001
Subdivision of PMXR, %	< 14.9	15.0-19.9	20.0-24.9	25.0-29.9	≥ 30.0
Affected articular surface % (cases)	7.65 (26) (± 6.92)	11.03a (18) (± 5.57)	14.31 (11) (± 6.34)	20.79a (14) (± 4.19)	27.87a (12) (± 10.78)

^aStatistically significant (P < 0.05) when compared to the previous group. PMXR: Profile X-ray images of the posterior malleolus.

Table 4 Relationship between the size of the posterior malleolus and the affected articular surface according to the Haraguchi classification

Classification	Haraguchi
	I	II	III	P value
Cases (%)	29 (35.8)	33 (40.7)	19 (23.4)	N/A
X-ray
PM size % (PMXR)	21.66a (± 9.91)	24.84a (± 9.03)	12.45 (± 4.17)	< 0.001
CT
Articular surface of the tibial plafond % (AXCT)	12.24 (± 5.47)	22.80 (± 8.28)	3.84 (± 2.78)	< 0.001

^aThere was a statistically significant difference only when compared to Haraguchi III. There was no significant difference between Haraguchi I and II; there was a statistically significant difference when all categories were compared. The P < 0.001 value was found when comparing the three groups and indicates a significant statistical difference. AXCT: Axial computed tomography slice of the posterior malleolus; CT: Computed tomography; N/A: Not applicable; PM: Posterior malleolus; PMXR: Profile X-ray images of the posterior malleolus.

Table 5 Articular surface of the posterior malleolus in axial computed tomography slices according to the Haraguchi classification

Haraguchi (n)	Size of the posterior malleolus, by X-ray
	< 25%, n = 56	≥ 25%, n = 25
I (29)	10.84% (± 3.74)a	15.29% (± 7.62)b
II (33)	17.99% (± 5.79)a	27.33% (± 7.81)b
III (19)	3.84% (± 2.78)a	-

^aP < 0.001.

^bP = 0.002.