Total hip arthroplasty (THA) is regarded as one of the most successful and cost-effective surgical procedures in end-stage hip arthritis [1][2][3] . THA effectively reduces pain, improves function, mobility and quality of life 3) . As health care continues to improve and life expectancy increases, the demand for total joint arthroplasty will rise to reflect this more active, aging population 2) . Internationally, the amount of THAs is expected to increase by 170% between now and 2030. In addition, an increasing number of THA require revision; total hip revisions are also projected to increase by 137% by 2030 2,[4][5][6][7] . Complications after THA can be very challenging for both the surgeon and the

PurposeThe purpose was to determine the proportion of native non‐arthritic knees that fit within the target zones of adjusted mechanical alignment (aMA), restricted kinematic alignment (rKA), and inverse kinematic alignment (iKA), and to estimate adjustments in native coronal alignment to bring outlier knees within the respective target zones. The hypothesis was that the target zone of iKA, compared to the target zones of aMA and rKA, accommodates a higher proportion of native non‐arthritic knees. MethodsThe study used measurements obtained from a computed tomography (CT) scan database (SOMA, Stryker) of 972 healthy knees (Caucasian, 586; Asian, 386). Hip knee ankle (HKA) angle, medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA) were used to estimate the proportions of knees within the patient‐specific alignment target zones; and to estimate theoretical adjustments of MPTA, LDFA and soft tissue balance (HKA) to bring outlier knees within target zones. Theoretical adjustments to bring outlier knees within the alignment target zones of aMA, rKA and iKA were calculated by subtracting the native coronal alignment angles (MPTAnative, LDFAnative and HKAnative) from angles on the nearest target zone border (MPTAtarget, LDFAtarget and HKAtarget). ResultsPatients were aged 59.8 ± 15.8 years with a BMI of 25.0 ± 4.4 kg/m2. The HKA angles were between 168° and 186°, MPTA between 78° and 98° and LDFA between 79° and 93°. Of the 972 knees, 81 (8%) were in the aMA target zone, 530 (55%) were in the rKA target zone, and 721 (74%) were in the iKA target zone. Adjustments of MPTA, LDFA and HKA angle to bring outlier knees within the target zones, were, respectively, 90, 91 and 28% for aMA, 45, 28 and 25% for rKA, and 25, 23 and 7% for iKA. ConclusionsThere is considerable variability in native knee coronal alignment that corresponds to different proportions of the restricted patient‐specific alignment target zones for TKA. Although extension of the MPTA and LDFA target zones with rKA accommodate native knee alignment better than aMA, up to 25% would require adjustment of native HKA angle. By also extending the HKA angle target zone into varus, iKA accommodates a greater proportion (93%) of native limb alignment. Level of evidenceIV.

Purpose: The issue of rising healthcare costs and limited resources is a worldwide discussed topic since the last decades. We hypothesized that failure of proximal humeral fracture osteosynthesis is presumed to be an important determinant in healthcare resources and related costs. The aim of this study was to calculate the total hospital related healthcare cost of proximal humeral fracture osteosynthesis over one year focussing on failure.Methods: 121 patients with a proximal humeral fracture treated by angular stable osteosynthesis were included in this retrospective study. All hospital related healthcare costs were investigated. Five main hospital related cost categories were defined: hospitalization cost, honoraria, day care admission, materials and pharmaceuticals.Results: A total healthcare cost of € 1.139.448 was calculated for the whole patient group. Twelve patients needed revision surgery due to complications or fixation related failure. This failure rate alone costed € 190.809 of the healthcare resources. In other words, failure after proximal humeral fracture osteosynthesis costed 17% of the total healthcare expenditure in one year. Conclusion:This study demonstrates that a high amount of hospital related healthcare resources is spent because of failure after proximal humeral fracture osteosynthesis. Further research is necessary and should investigate on how to prevent failure. This is not only in the patient's interest, but it is of great importance for maintaining a healthy healthcare system.

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