Descriptive characteristics of the cohort:
A total of 34 patients with operatively treated tibial plafond fracture could be re-examined. The average age of the study group, consisting of 8 women and 26 men, was 44.6 years at the time of surgery (SD: 11.87, range: 21-64). Patients averaged 26.8 kg/m² in BMI (SD: 3.46, range: 20.96-36.51). The average period between surgery and follow-up was 63.97 months (SD: 31.79, range: 24-131).
Referring to the AO/OTA Classification, 20 of the patients had type B fractures and 14 suffered from type C fractures. In Group I there were 11 type B fractures and 4 type C fractures. In Group II there were 9 type B fractures and 10 type C fractures.
Olerud & Molander and Short-Form-36:
On average, the patients surveyed scored 69.12 points (SD: 24.79, range: 10-100) in the O & M score. The comparison of both groups according to the reduction quality is shown in Table 1 below. In the SF-36 survey, the PCS averaged 48.25 points (SD: 10.6, range: 25.22-60.77) and the MCS 50.65 points (SD: 9.58, range: 27.22-64.83). The PCS score distribution in the two groups is shown in Table 2.
Grade of osteoarthritis:
Figure 1 shows the categorization of the two patient groups according to their grade of osteoarthritis classified by Kellgren and Lawrence.
Range of motion:
Figure 2 shows the number of patients with the deficit of range of motion depending on the group affiliation for the reduction result.
Pain intensity:
The mean value for the intensity of pain, according to the VAS, was 2.88 and the median was 2.5 (SD: 2.57, range: 0-8). The illustration of the group-specific results for the VAS is shown in Table 3.
Group-specific comparison concerning reduction quality:
The O & M score could be significantly influenced by the reduction quality (p=0.000): The mean difference was 33.79 points (SE: 6.32).
Significant association of SF-36 score with reduction quality could also be observed (p=0.001 to p=0.02; without MCS domain): In the comparison of the PCS domain, the mean difference amounted to 10.24 points (p=0.003; SE: 3.25). There were no significant differences with regard to the MCS domain of the SF-36 score (p=0.142).
There were significant differences of movement deficit when reduction quality was compared (p=0.001): The mean ranks of the good reduction group were lower (11.50°) than the mean ranks of the suboptimal reduction group (22.24°).
Significant deviation in pain level, captured by VAS, depending on reduction quality (p=0.001) was found: The mean difference was 2.77 (SE: 0.76).
A significantly different distribution between Group I and Group II concerning the grade of osteoarthritis (p=0.005) could be seen (Figure 1).
In summary, the group with the anatomically more accurate reduction showed a better result in terms of clinical follow-up and quality of life except for the MCS domain of the SF-36.
Group-specific comparison concerning descriptive parameters:
No significant differences could be found concerning age (p=0.836), sex (p=0.231), BMI (p=0.151), type of fracture (p=0.127) or period between surgery and follow-up (p=0.996) in the groups differentiated according to reduction quality.
Significant distribution differences were observed with regard to nicotine abuse (p=0.002), profession with heavy physical work (p=0.014) and concomitant injuries (p=0.004), whereby these were predominantly found in the suboptimal reduction group (Group II).
Nicotine consumption had a significant influence on the O & M score (p=0.003) and the profession category with heavy physical stress showed a significant influence on the movement deficit (p=0.000), which in each case was associated with a worse outcome. The degree of concomitant injuries correlated negatively with the O & M score (p=0.009, r=-0.442) as well as with the Role Physical domain of SF-36 (p=0.042, r=-0.351) and was associated with a worse result in the range of motion (p=0.008, r=0.446) along with the pain intensity (p=0.005, r=0.472). The other parameters remained unaffected.
A correlation between the period for the follow-up examination and the individual examination parameters could not be observed either (p=0.200-0.937, r=0.160).
Group-specific comparison concerning type of articular surface irregularities:
Table 4 lists the descriptive statistics regarding the O & M scores depending on the type of articular surface irregularity. Only the group of patients with steps differed significantly from those with the combination of gaps and defects (p=0.034). None of the other groups provided significant differences regarding the comparison of their mean values in the O & M scores.
When parameters (SF-36, range of motion, arthrosis, VAS) were considered, no significant differences could be found concerning the different types of joint surface irregularities (p=0.076-0.234).
Group-specific comparison concerning size of articular surface irregularities:
The width of the gaps ranged from 0 to 8.3 mm (SD: 1.74), the range of defects was 0 to 9 mm (SD: 2.7) and the steps varied from 0 to 4.7 mm (1.27).
The correlations between the O & M Score and the step, gap, and defect sizes revealed the results listed in Table 5, whereby only the defect size correlated significantly (p=0.005; r =-0.470) with the O & M Score. The score decreased with increasing defect size.
The correlation analysis according to Pearson regarding the size of the specific joint surface irregularities and the six domains of the SF-36 score did not yield any significant results.
The irregularity sizes correlated with the movement deficits. Only the defect size demonstrated significant results in the correlation analysis with the extension deficit (p=0.038; r=0.358), the flexion deficit (p=0.041; r=0.353), and the total deficit (p=0.013; r=0.420). The Spearman coefficients were positive.
The step size (p=0.807) and defect size (p=0.084) did not correlate significantly with the grade of osteoarthritis. However, the gap size correlated significantly (p=0.035) and the Spearman coefficient was positive. A larger gap in the articular surface resulted in a higher grade of osteoarthritis.
The VAS did not correlate significantly with either the step size or the gap size. The defect size, however, showed a significant result (p=0.012). The Pearson coefficient was positive (r=0.425). It could therefore be concluded that larger defects were associated with higher values on the VAS.
Most important influencing factor related to the outcome:
According to the multivariate linear regression analyses of this study, the reduction quality had the greatest influence on the functional result after operatively treated tibial plafond fracture determined by the O & M score (p=0.001) and the PCS domain of the SF-36 score (p=0.018).