We retrospectively reviewed 82 adult patients with 86 distal femur fractures treated with fixed-angle lateral locking plates between 2003 and 2008 at two institutions, The University of Iowa Hospitals and Clinics (73 fractures) and the Slocum Center for Orthopaedics (13 fractures). We excluded 11 patients without radiographs at a minimum of 12 weeks after injury, leaving 71 study patients with 75 fractures. Two of these 11 patients died in the early postoperative period, four had documented transfer of care out of state, and the remaining five had limited followup of less than 12 weeks. Forty-six of the 71 patients (64%) had clinical and radiographic followup at 1 year or longer after injury. Twenty-five additional patients in the group of 71 had clinical and radiographic followup at greater than 12 weeks but less than 1 year after injury and were contacted by telephone. They were asked the following questions: Have you had any other operations on your knee? If yes, what kind? Have you seen an orthopaedic surgeon for your knee? Do you use any walking aids specifically for your knee? Are you currently working or back to recreational activities? If not, why? The questions were designed to identify any issues that would be expected in patients with failure of fracture healing after their injury. Based on the responses to this questionnaire, five additional patients were eliminated because the healing outcome of their femur fracture was considered uncertain. This patient questionnaire at longer-term followup was used as a surrogate for observing fracture healing on radiographs as the expense, inconvenience, and radiation exposure for patients to achieve long-term followup radiographs years after their injury could not be justified. The final study population was 66 of the 82 patients (80%) with 70 fractures. The time of followup for telephone interviews and SF-36v2TM
scores was a minimum of 1 year (mean, 4.2 years; range, 1–7.2 years). There were 10 periprosthetic fractures, all of which were Rorabeck Type II fractures with well-fixed components [26
]. The study was approved by the Institutional Review Board at both institutions.
The procedures were performed by or under the supervision of an orthopaedic trauma surgeon at both institutions. The time from injury to applying the locking plate ranged from 0 to 10 days, with an average of 2.8 days. Nine patients had external fixators placed before definitively fixing the fracture, and 18 had irrigation and débridement for an open fracture. Plates were placed through small 4- to 6-cm incisions, and the metaphyseal portion of the fracture was reduced closed in 52 fractures and open in 18 fractures. No acute bone grafts were performed. None of the periprosthetic fractures required revision of components.
Patients were mobilized wearing a hinged knee brace on the first postoperative day. Deep venous thrombosis prevention measures were provided, most commonly aspirin and mechanicals.
Patients typically were seen for followup at 2 weeks, 6 weeks, 3 months, 6 months, and 1 year after injury with clinical examination and radiographs performed each time with the exception of the initial postoperative visit. We reviewed the medical records and radiographs of all patients and recorded demographic data, injury mechanism, time to weightbearing, ability to bear weight, and complications. Charts were reviewed for smoking history by answering yes or no. Patients were contacted by telephone or mail to obtain SF-36v2TM
]. These scores were compared with published US age-matched normative data [33
surveys were obtained for 44 of the 66 patients (67%), and the average physical component score (PCS) and mental component score (MCS) were calculated. All outcomes scores were for healed fractures; two patients who initially had nonunions were included because they had been treated successfully with revision surgery and had achieved healing. Surgical site infections were determined according to the Centers for Disease Control and Prevention definition as superficial or deep [10
]. The specific plate used and the construct material (stainless steel versus titanium) were identified (Table ).
Locking plate design, manufacturer, and material used in this study
Radiographs were assessed for fracture classification, alignment, change in alignment, healing, and callus formation. All fractures were classified on injury radiographs using the OTA/AO Universal fracture classification [24
], and open fractures were classified by the Gustilo and Anderson system [8
] (Table ). The fractures were divided into those without substantial metaphyseal comminution (33A1, A2, and C1; n = 33) and those with metaphyseal comminution (33A3, C2, and C3; n = 42).
Characteristics of supracondylar femur fractures
One of us (CEH) measured alignment of the fracture on postoperative AP and lateral radiographs of the femur and knee. Normal coronal alignment was considered 5° to 7° valgus, and normal sagittal alignment was neutral. Malalignment was defined as greater than 5° deviation from normal coronal or sagittal alignment [25
]. Loss of alignment was defined as greater than a 3°-change in angular measurements between postoperative and followup radiographs.
Six-week postoperative radiographs were assessed for plate length, bridge span length, and number of holes left unfilled adjacent to the fracture or area of comminution. The bridge span length was defined as the distance (millimeters) between screws adjacent to the fracture; two groups were formed by comparing those with above-average bridge spans (> 69 mm, n = 26) with those with below-average bridge span length (< 69 mm, n = 44). A screw hole was counted as unfilled adjacent to the fracture if, at the site of an empty hole, a perpendicular screw path would encounter only intact cortical bone avoiding any comminution. Two groups were formed for analysis, those with zero holes left unfilled (n = 27) versus those with two or more holes left unfilled (n = 13). Fractures with only one unfilled hole were not included in this analysis to allow comparison between two groups with different mechanical properties. The ratio of bridge span to plate length also was compared between groups.
Serial orthogonal radiographs taken at 6 weeks, 3 months, and 6 months after the fracture were reviewed by one observer (CEH) who was not a treating surgeon, to assess union by identifying bridging callus of at least two cortices [12
]. Patient charts were reviewed for documentation of the ability to bear weight without pain. The formation of bridging callus on radiographs and the ability to bear weight without pain are the most frequently used criteria for fracture union in reported clinical series and were used in this study [3
]. Cortical bridging observed on radiographs is reportedly the most reliable assessment of fracture healing [35
]. Nonunion was defined by pain with weightbearing and the absence of progressive fracture healing or bridging callus at the medial cortex on serial radiographs.
The amount of callus formed on the anterior, posterior, and medial sides of the fracture opposite the locking plate was measured on radiographs at 6, 12, and 24 weeks after injury in 63 fractures. To measure callus, the serial radiographs had to meet strict criteria such as consistent rotation, which resulted in eliminating seven fractures. An established algorithm was used to objectify the measurement of callus size [18
]. Briefly, custom software extracted the size of periosteal callus from plain radiographs without the need for manual tracing of callus boundaries. Callus size was converted to metric area using a length standard based on implant features. The algorithm was determined to measure callus area in surrogate models with an error less than 5% [18
]. For clinical oversight, three clinicians independently inspected the demarcation of cortical bone and periosteal callus in every analyzed image in a validation protocol [18
]. The actual callus measurements for the radiographs in this study were made by an independent observer (TJL) not involved in patient care.
The primary outcome was presence or absence of fracture healing determined by clinical and radiographic review. The individual values of patient age, ISS, bridge span length, and number of unfilled holes adjacent to the fracture were obtained and means were calculated [1
]. Fractures were divided into two groups based on whether they were healed. Comparisons then were performed using Fisher’s exact test for categorical variables such as smoking status and Student’s t test for continuous variables such as patient age. All tests were two-tailed. The effect of factors on time to weightbearing and time to bridging callus was assessed with Fisher’s exact test. The effect of factors on callus size was determined with ANOVA (SPSS statistics, SPSS Inc, Chicago, IL, USA).