SLR - August 2013 - Jessica L. Minder
Reference: Lee KT, Park YU, Jegal H, Park JW, Choi JP, Kim JS. Foot Ankle Int. 2013 May;34(5):691-6. doi: 10.1177/1071100713475349. Epub 2013 Feb 4.
Scientific Literature Review
Reviewed by: Jessica L. Minder, DPM
Residency Program: Inova Fairfax Hospital
Podiatric Relevance: There have been several reports discussing the classification and treatment of fractures occurring in the proximal part of the fifth metatarsal. Regarding treatment, Torg postulated that the selection of the best form of treatment for such proximal fifth metatarsal fractures should be based on the presence or absence of medullary sclerosis adjacent to the fracture site. Yet many surgeons continue to report poor outcomes for Torg type I and type II fractures, even after surgery, and diverse results continue to appear amongst patients with the same Torg type classification. A 2011 study by Lee et. al. reported the plantar fracture gap as another poor prognostic factor for healing of fifth metatarsal stress fractures. As the Torg classification does not consider the plantar fracture gap in its decision-making process for surgery or as a prognostic indicator, the authors have proposed a new classification system for fifth metatarsal stress fractures using morphology of the fracture and size of the plantar gap in its criteria.
Methods: Eighty-six cases with a fifth metatarsal fracture distal to the tuberosity were included, each surgically managed with tension band wiring. Each case was classified according to Torg’s classification and the author's proposed classification. The proposed classification system divides cases into two groups according to morphology of the fracture and presence or absence of a plantar gap greater than one millimeter: Group A (complete fracture group) and Group B (incomplete fracture group). The patients of Group A were subdivided into two groups according to fracture morphology: Group A1 (acute fracture) and Group A2 (acute on chronic fracture). Group B was subdivided into two groups according to the plantar gap: Group B1 (plantar gap less than one millimeter) and Group B2 (plantar gap one millimeter or greater). The time for bone union was calculated and compared, both among Torg’s classification, and among the authors' proposed classification.
Results: The mean time for bone union for each Torg type was 65.2 ± 19.6 days for type I, 95.4 ± 48.3 for type II, and 109.25 ± 48.31 for type III. There was a significant difference in the time for bone union among the three Torg types (p = 0.004).
Using the authors' proposed classification, the mean time for bone union in Group A (complete fracture) was 67.5 ± 28.8, and it was 103.2 ± 47.7 for Group B (incomplete fracture), a significant difference (p < 0.001). The mean time for bone union in Group A1 (acute fracture) was 66.3 ± 20.2, and it was 69.7 ± 41.9 for Group A2 (acute on chronic fracture), not reaching statistical significance. The mean time for bone union in Group B1 (plantar gap less than one millimeter) was 73.9 ± 26.7, and it was 115.5 ± 45.4 for Group B2 (plantar gap one millimeter or more). There was a significant difference between Groups B1 and B2 (p < 0.001). On repeat analysis to eliminate the variable of bone grafting, all Torg type III fractures were eliminated, and similar trends remained.
There were eight cases of nonunion in the Torg type II and one case in type III. According to the new classification, there was one case in Group A and eight cases in Group B, all in Group B2.
Conclusions: Based on these findings, the authors' proposed classification system has improved prognostic ability and treatment implications over the Torg system, due to its addition of plantar gapping criteria. Limitations of this study include the absence of consideration of other factors that can affect the time for bone union, limited control on the activity level of patients, and small sample size.