Experimental study of risk of medial hinge fracture during distal femoral varus osteotomy.

INTRODUCTION: Lateral opening wedge distal femoral osteotomy (LOWDFO) is indicated for isolated lateral osteoarthritis in the valgus morphotype. Medial hinge fracture is a factor for poor prognosis. The present study had two aims: (1) to assess the impact of a temporary K-wire on hinge fracture risk; and (2) to assess the impact of LOWDFO opening speed. HYPOTHESIS: The main study hypothesis was that a temporary hinge K-wire reduces hinge fracture risk. The second hypothesis was that faster opening speed increases fracture risk. MATERIAL AND METHOD: Twenty femurs were produced by 3D printing from a CT database, reproducing LOWDFO anatomy. The ABS® polymer showed the same breaking-point behavior as human bone. Ten specimens were included in the "K-wire" group (KW+) and 10 in the "No K-wire" group (KW-). To determine high and low speed, a motion-capture glove was used by 2 operators, providing 3D modeling of the surgeon's hand. High speed was defined as 152mm/min and low speed as 38mm/min. The KW+ and KW- groups were subdivided into high- and low-speed subgroups (HS, LS) of 5 each. Compression tests were conducted using an Instron® mechanical test machine up to hinge fracture. The main endpoint was maximum breaking-point force (N); the secondary endpoints were maximum displacement (mm) and maximum speed (min) at breaking point. RESULTS: The K-wire significantly increased maximum breaking-point force (LS, 143.08N vs. 93.71N, p<0.01; and HS, 186.98N vs. 95.22N, p<0.01), but not maximum displacement (LS, 26.17mm vs. 24.11mm, p=0.31; and HS 26.18mm vs. 23.66mm, p=0.14) or maximum time (LS, 27.07s vs. 24.94s, p=0.31; and HS, 5.24s vs. 4.73s, p=0.14). Speed did not affect maximum force (KW+, 143.08N vs. 186.98N, p=0.06; and KW-, 93.71N vs. 95.22N, p=0.42) or maximum displacement (KW+, 26.17mm vs. 26.18mm, p=1; and KW-, 24.11mm vs. 23.66mm, p=0.69). Only maximum time was greater at low speed (KW+, 27.07s vs. 5.24s, p>0.01; and KW-, 24.94s vs. 4.73s, p<0.01), which is obvious for constant distance. DISCUSSION: The first study hypothesis was confirmed, with significantly lower hinge fracture risk with the K-wire, independently of opening speed. The second hypothesis was not confirmed. The study was performed under strict experimental conditions, unprecedented to our knowledge in the literature. However, complementary clinical studies are needed to confirm the present findings. LEVEL OF EVIDENCE: IV, experimental study.

Post-traumatic elbow osteoarthritis after radial head arthroplasty: Prevalence and risk factors.

BACKGROUND: One of the treatment options for comminuted radial head fractures is radial head arthroplasty (RHA), especially when the elbow is also dislocated. While the clinical outcomes of RHA have been well documented, the incidence of post-traumatic osteoarthritis after RHA and its risk factors are not well known. OBJECTIVE: To determine the incidence of post-traumatic elbow osteoarthritis (humeroulnar and humeroradial joints) after RHA and identify its risk factors. METHODS: All patients who underwent RHA at our hospital between 2008 and 2016 were included retrospectively. The inclusion criteria were primary RHA, recent radial head fracture (isolated or associated with elbow dislocation), minimum 1 year of follow-up, clinical and radiographic examination at final assessment. The exclusion criteria were pre-existing elbow osteoarthritis, RHA revision, multiple fractures of the ipsilateral upper limb or polytrauma. The final assessment consisted of a clinical examination [joint range of motion (ROM) and Mayo Elbow Performance Score (MEPS)] and standard radiographs. The correlation between the incidence and severity of osteoarthritis and various risk factors was determined. RESULTS: Seventy-three patients were included in the analysis with a mean age of 56 years (21-85). The injuries consisted of 41 terrible triad, 15 isolated radial head fractures, 11 Monteggia fractures and 6 transolecranon fracture-dislocations. The mean follow-up was 3.4 years (1-10.9). At the final assessment, osteoarthritis was visible in the humeroulnar compartment in 56% of cases and in the humeroradial compartment in 72% of cases. There was a statistical correlation between the presence of humeroulnar osteoarthritis at the final assessment and ROM in flexion-extension (p=0.003), MEPS (p<0.001), duration of immobilization (p=0.03) and presence of posterior subluxation on immediate postoperative radiographs (p=0.012). The correlation between humeroradial osteoarthritis at the final assessment and ROM in flexion-extension (p=0.0054), RHA implant position (p<0.01), and unipolar configuration (p=0.027) was statistically significant. CONCLUSION: In our study, elbow osteoarthritis incidence after RHA was 56% in the humeroulnar joint and 72% in the humeroradial joint. RHA implant placement, posterior subluxation immediately postoperative and the duration of immobilization were significantly corelated with osteoarthritis. LEVEL OF EVIDENCE: IV; case series without control group.

Prognostic factors for traumatic elbow osteoarthritis after terrible triad surgery, and functional impact.

INTRODUCTION: Terrible triad (TT) of the elbow almost always requires surgery to prevent progression to chronic instability and more or less inevitable osteoarthritis. Progression toward osteoarthritis after well-conducted surgery and associated risk factors have been little reported. We performed a retrospective study: (1) to assess rates of post-traumatic elbow osteoarthritis after surgical treatment of TT; (2) to assess functional impact; and (3) to identify prognostic factors. HYPOTHESIS: Prevalence of osteoarthritis after surgical treatment of TT is high, impairing functional results. MATERIAL AND METHOD: A single-center retrospective study included 53 patients, with a mean age of 50±17.8 years (range, 21-84 years), undergoing surgery for acute TT in our department. All received clinical examination with ranges of motion and Mayo Elbow Performance Index (MEPI) and radiographic assessment at a minimum 1 year's follow-up. Osteoarthritis at last follow-up was assessed on elbow X-ray in the humero-ulnar and radio-condylar compartments on the Broberg-Morrey classification. Functional impact on range of motion and MEPI and prognostic factors were assessed on Student test or ANOVA and Chi2 or Fisher test. RESULTS: Prevalence of Broberg-Morrey grade 2 or 3 osteoarthritis was 45.3% (24/53) in the humero-ulnar compartment and 50% (25/50) in the radio-condylar compartment. Humero-ulnar osteoarthritis impaired MEPI (76.3 points with versus 88.4 points without; p=0.003), flexion-extension (102.3° versus 115.2°; p=0.043) and pronation-supination (138.8° versus 159.3°; p=0.006). Radio-condylar osteoarthritis had no significant impact on MEPI (81.4 points with and 84.4 points without; p=0.47), flexion-extension (104.8° and 113°; p=0.23) or pronation-supination (141.8° and 156.4°; p=0.2). Humero-ulnar osteoarthritis at last follow-up was associated with dislocation or subluxation on immediate postoperative lateral view (45.8% with versus 10.3% without; p=0.004) and at last follow-up (20.8% versus 3.4%; p=0.047) and with postoperative complications (54.2% and 27.6%; p=0.049). Radio-condylar osteoarthritis at last follow-up was associated with radial head replacement rather than internal fixation (respectively, 92% and 48%; p=0.0007) and excessively high radial head implant positioning (47.8% versus 0%; p=0.023). CONCLUSION: Prevalence of traumatic osteoarthritis after TT surgery was high, at 45.3% in the humero-ulnar compartment and 50% in the radio-condylar compartment, with clinical impact in humero-ulnar involvement. LEVEL OF EVIDENCE: IV; cohort study without control group.