Using a fracture gap at least 1 cm in length involving
more than 50% of the cortical diameter as a definition for a critical-sized
defect of the tibia does not ensure reoperation rate, according to a recently
David Sanders, MD, shared his group’s findings at
2011 Annual Meeting of the American Academy of Orthopaedic
“The management of traumatic bone defects is
controversial,” Sanders said. “Two primary strategies are to just
watch and wait vs. doing some type of
bone grafting or other procedure on an immediate basis. The
difficult in interpreting previous studies is the natural history is unknown
— as well as the clinical significance.”
Combing through the SPRINT trial
Sanders and his group investigated the 1,225-patient
SPRINT trial for literature involving critical defects. They
defined a critical defect as one that was not expected to heal in the absence
of secondary intervention. Using a definition of critical defects involving
more than 50% of the cortical diameter of the tibia and being greater than 1 cm
in length, the group set out to “ascertain the significance of these
critical-sized defects in terms of the rate of secondary surgery, which factors
are associated with non-union and the overall outcome of the patients
involved,” Sanders said.
Patients in the study were evaluated for secondary
interventions to gain union such as bone grafting,
bone transport and
“We also made a strict definition for planned vs.
unplanned surgery,” Sanders said. “Planned being something performed
according to institutional protocol at the time of initial injury vs. unplanned
surgery being something performed to correct the non-union once it
The group compared patients with bone defects to those
in the overall SPRINT cohort, then looked within the bone defect cohort to
compare those who had a reoperation vs. those who did not. Both comparisons,
Sanders said, included issues relating to patient demographics, fracture
characteristics, surgical factors, and 1-year function.
Results and findings
“Of the 1,225 patients in the trial, only 37 had a
critical-sized defect,” Sanders reported. “Of these, seven had a
planned reoperation according to institutional protocol.”
Sanders also reported that of the remaining 30 patients,
14 healed primarily without the need for reoperation, “suggesting there is
an overall 47% primary union rate on these patients with so-called
Reoperations included bone grafts, implant exchanges,
fracture site debridements, occasional shortening and synostosis procedures.
Patients with a defect had worse overall functional outcomes — displaying
SF-36 scores around five points lower on average.
Within the cohort of patients with a bone defect,
comparing those who had no reoperation with those who required a reoperation
revealed patients were less likely to require a reoperation to gain union if
they were female or if a reamed nail was utilized at the time of the index
“Patients with a reamed nail had a 64% primary
union rate compared with a 26% in the unreamed group,” Sanders said.
Size not necessarily critical
Sanders said it is important to note that the definition
of a critical-sized defect used within this study did not ensure reoperation
and added that further research is warranted.
These bone defects “are obviously clinically
important, with lower rates of union compared to tibial fractures without
defects — and worse functional outcomes compared to the overall
cohort,” he concluded. “However, defining a critical-sized bone
defect as a 1-cm longitudinal defect involving 50% or greater of the cortical
diameter might be overestimating things a bit. We had a primary union rate of
47%, suggesting this size defect is not necessarily critical.” —
by Robert Press
- Sanders D, Swiontkowski MF. The critical sized defect in the tibia:
Is it critical? Results from the SPRINT trial. Paper #382. Presented at the
2011 Annual Meeting of the American Academy of Orthopaedic Surgeons. Feb.
15-19. San Diego.
- David Sanders, MD, can be reached at the London Health Sciences
Centre, London, Ontario, Canada N6A 465; email:
- Disclosure: Sanders is a paid consultant for Smith &
Nephew and receives research or institutional support from Smith & Nephew
This is an important article as it emphasizes the need to be patient
with tibial defects with 50% of cortical loss and defect length of 1 cm or
greater. There has been a move to perform reoperations early (as early as 3
months) in delayed unions, as many surgeons felt they can predict a bad outcome
at 3 to 6 months. This article clearly illustrates a wait of 6 to 9 months may
be more appropriate as long as the patient’s symptoms are not increasing.
This level 1 evidence would indicate we could avoid surgery on 50% of the
patients in the group and 64% of a subset of patients who had received a reamed
One of the more promising findings is that the response to later
intervention remained high when performed with an exchange nail. The savings to
the patient and the health care system are obvious.
— Ross K. Leighton, MD, FRCS
Elizabeth II Health Sciences Centre
Division of Orthopaedic Surgery
Halifax, NS, Canada