Between January 2005 and February 2010, thirty-four patients with an open fracture of the proximal tibia were treated using the MIPO technique at our institution; of these 34 patients, 30 were followed for over 1 year. There were 24 men and 6 women of overall mean age 44.4 years (range, 24 to 69 years). The mechanisms of injuries were; a traffic accident in 24, a crushing injury in 5, and a fall from a substantial height in one. Eighteen of the 30 had an associated injury or fracture. The institution approved the study, which was conducted in strict adherence with established guidelines for treatment of subjects, and written informed consent was obtained from each patient.
According to the AO Foundation and Orthopaedic Trauma Association (AO-OTA) classification, 3 patients were of type 41-C, 6 were of type 42-A, 8 were of type 42-B, and 13 patients were of type 42-C. Open fractures were classified using the Gustilo-Anderson classification, and there were 11 patients with grade I, 6 patients with grade II, and 13 patients with grade III (III-A, 6; III-B, 6; III-C, 1) ().
Background Information on the Patients Enrolled in the Study
All patients were treated initially by radical wound debridement. If necessary, early soft tissue coverage was performed using a rotational gastrocnemius or soleus muscle flap. One case with a grade III-C open fracture underwent wound irrigation and debridement followed by vascular bypass surgery to re-establish arterial flow.
Two types of anatomical pre-contoured locking plates (locking compression plate-proximal lateral tibia [LCP-PLT], Synthes, West Chester, PA, USA; Zimmer periarticular locking plate [ZPLP], Zimmer, Warsaw, IN, USA) were used. LCP-PLT, which is composed of titanium alloy, has combi-holes, which allows placing either conventional or locking screw in every hole. On the other hand, ZPLP, stainless steel construct, has separated screw holes for conventional and locking screw, and locking screws in metaphyseal region have cannula inside that they can be placed accurately through the guide pins. All locking plates were placed on the lateral side of the proximal tibia. Plate lengths were selected to obtain a minimum of three good bicortical screw purchases distal to the fracture. An additional medial locking plate was fixed using the MIPO technique, if needed. Great care was taken to handle soft tissue gently and to minimize soft tissue damage.
When the open wound did not involve the lateral side of proximal tibia or the soft tissue or flap was considered sufficient ( and ), we performed simultaneous plate fixation with a soft tissue procedure, defined as primary MIPO. However, in cases with inadequate soft tissue coverage, given the need for a brief operation due to general medical condition, and the presence of a severely contaminated wound, patients were treated by staged MIPO. Temporary external fixation was done with soft tissue procedure initially, and subsequent definitive treatment was performed with a locking plate using the MIPO technique after soft tissue reactions have subsided. During our initial experiences, a staged procedure was adopted routinely ( and ), but as experience accumulated, primary MIPO was performed predominantly.
(A, B) A 53-year-old male patient sustained type III-B open proximal tibial fracture. (C, D) Primary minimal invasive plate osteosynthesis was performed and followed by rotational gastrocnemius muscle flap.
Follow-up radiograph after 1 year shows solid union of fracture (A, B) with an excellent function (C, D).
(A, B) A 51-year-old male patient suffered from type III-A open proximal tibial fracture. (C, D) Knee bridging external fixation was performed after wound debridement and closure on that day.
(A-C) After wound was healed at 13 days, minimal invasive plate osteosynthesis was done. (D) Satisfactory alignment was achieved. (E, F) Follow-up radiograph after 3 years shows complete union of fracture.
Postoperative Care and Assessment
Rehabilitation was started on the second postoperative day with quadriceps setting and continuous passive motion of the knee joints. After discharge, the patients were encouraged to perform straight leg-raising exercise and active flexion of their knees and ankles, from tolerable range of motion followed by gradual increase of range similar to unaffected limb. Toe-touch weight bearing with crutches was started at approximately 4 weeks postoperatively, and limited weight bearing was allowed only after obtaining radiographic evidence of healing. Routine follow-up radiographs were obtained every 6-8 weeks until solid continuous callus formation was observed; callus formation on 3/4 cortices and radiographic evidence of fracture line fading were considered signs of fracture union. Frontal and sagittal plane angulations were assessed on anteroposterior and lateral plain radiographs obtained immediately after surgery and at final follow-up visits. Knee and ankle ranges of motion, limb rotations and alignments, and signs of implant-associated were checked at all follow-up visits. Final clinical outcomes were evaluated using Knee Society clinical rating scores,11)
where excellent means 85-100; good, 70-84; fair, 60-69; and poor < 60.
Complications were recorded as union or soft tissue related, including infection. A superficial infection was defined as local cellulitis with or without serous discharge treated with oral antibiotics. Any infection that warranted operative debridement was considered a deep infection.12)
The chi-square test and regression analysis were used to determine the natures of relations between final clinical outcomes, complications, and possible influencing factors, such as fracture pattern (AO-OTA), open fracture grade (Gustilo-Anderson), operative method (primary or staged MIPO), and type of implant used. The analysis was conducted using SPSS ver. 17.0 (SPSS Inc., Chicago, IL, USA), and statistical significance was accepted for p-values < 0.05.