A propensity score-matched analysis on the impact of patient and surgical factors on early periprosthetic joint infection in minimally invasive anterolateral and transgluteal total hip arthroplasty.

INTRODUCTION: Increased risk of periprosthetic joint infection (PJI) in minimally invasive (MIS) total hip arthroplasty (THA) is still debated. This study aimed to identify differences in surgical and patient-related risk factors for PJI between an MIS anterolateral approach and transgluteal-modified Hardinge approach. METHODS: A retrospective cohort of 5315 THAs performed between 2006 and 2019 at a single institution was screened. Short stem THAs performed via an MIS anterolateral approach in the supine position and standard straight stem THAs performed via a transgluteal modified Hardinge approach were included. Propensity score matching was performed to control for selection bias. After matching, 1405 (34.3%) short stem THAs implanted via MIS anterolateral approach and 2687 (65.7%) straight stem THAs implanted via a transgluteal modified Hardinge approach were included. The risk of PJI due to patient-specific and surgical factors was retrospectively analyzed using chi-square test and multivariate regression analysis. RESULTS: PJI occurred in 1.1% in both MIS anterolateral and transgluteal approach (p = 0.823). Multivariate regression showed an increased infection risk for patients with a BMI between 35 and 39.99 kg/m2 (OR 6.696; CI 1.799-24.923; p = 0.005), which could not be demonstrated for transgluteal approach (OR 0.900; CI 0.900-4.144; p = 0.93). A BMI ≥ 40 kg/m2 (OR 14.150; CI 2.416-82.879; p = 0.003) was detected as a risk factor for PJI only in anterolateral approach. Increased operation time ≥ 121 min showed a significantly increased risk for PJI in the general cohort (OR 6.989; CI1.286-37.972; p = 0.024). CONCLUSION: Minimally invasive anterolateral and transgluteal THA show a comparable rate of early PJI within the first year of index surgery. A BMI of ≥ 35 kg/m2 was detected as a clear risk factor for infection in the anterolateral approach. Prolonged operation time ≥ 121 min increases the risk of PJI regardless of approach.

Cementless femoral stem revision in total hip arthroplasty: The periprosthetic clamshell fracture. A biomechanical investigation.

To biomechanically evaluate the stability of a diaphyseal anchored, cementless stem in presence of a proximal periprosthetic femoral medial wall defect compared to the stability of the same stem in an intact femur. Twenty-two paired human cadaveric femora were pairwise assigned either to a fracture group, featuring a proximal medial wall defect involving 40% of the stems medial anchorage distance, or a control group with native specimens. The specimens were tested under a monotonically increasing cyclic axial loading protocol. Load, cycles, and multiples of the respective body weight at implant loosening was measured. Mean initial stiffness was 2243.9 ± 467.9 N/mm for the intact group and 2190.1 ± 474.8 N/mm for the fracture group. Mean load to loosening in the intact group was 3210.5 ± 1073.2 N and 2543.6 ± 576.4 N in the fracture group, with statistical significance. Mean cycles to loosening in the intact group were 27104.9 ± 10731.7 and 20431.5 ± 5763.7 in the fracture group, with statistical significance. Mean multiples of the resulting body weight at loosening in the intact group was 548.3 ± 158.5% and 441.4 ± 104% in the fracture group, with statistical significance. A medial wall defect involving 40% of the medial anchorage distance significantly decreases the axial stability of a diaphyseal anchored stem. However, mechanical failure occurred beyond physiological stress. At loosening rates of about 4 multiples of the body weight in the fracture group, a "safe zone" remains of a 0.5-fold body weight for maximum loads and twofold body weights for average loads.

The race for the classification of proximal periprosthetic femoral fractures : Vancouver vs Unified Classification System (UCS) - a systematic review.

BACKGROUND: Periprosthetic femoral fractures (PFFs) represent a major cause for surgical revision after hip arthroplasty with detrimental consequences for patients. The Vancouver classification has been traditionally used since its introduction in 1995. The Unified Classification System (UCS) was described in 2014, to widen the spectrum by aiming for a more comprehensive approach. The UCS also aimed to replace the Vancouver classification by expanding the idea of the Vancouver classification to the whole musculoskeletal apparatus. After introduction of the UCS, the question was raised, whether the UCS found its place in the field of analysing PFFs. Therefore, this systematic review was performed to investigate, the use of the UCS compared to the established Vancouver classification. METHODS: Medline was searched for reports published between 1 January 2016 and 31 November 2020, without language restriction. Included were original articles, irrespective of the level of evidence and case reports reporting on a PFF and using either the Vancouver or the UCS to classify the fractures. Excluded were reviews and systematic reviews. RESULTS: One hundred forty-six studies were included in the analysis. UCS has not been used in a single registry study, giving a pooled cohort size of 3299 patients, compared to 59,178 patients in studies using the Vancouver classification. Since 2016, one study using UCS was published in a top journal, compared to 37 studies using the Vancouver classification (p=0.29). During the study period, the number of yearly publications remained stagnant (p=0.899). CONCLUSIONS: Despite valuable improvement and expansion of the latter UCS, to date, the Vancouver system clearly leads the field of classifying PFFs in the sense of the common use.

Short Term Results of Early Treatment of Developmental Dysplasia of the Hip or Luxation with Pavlik Harness in Human Position.

Background and Objectives: This study shows a sufficient treatment with the Pavlik harness for all patients through all phases of developmental dysplasia of the hip (DDH) if there is a strict regime. Materials and Methods: There was an ultrasound measurement stage of IIc or worse (D, IIIa/b, IVa/b) in 159 out of 7372 newborns between 1995 and 2006 (2.15%). This is an indication for treatment with the Pavlik harness. Overall, 203 dysplastic hips were treated initially with our regime. After detection, we started the application of the Pavlik harness immediately in the 'human position'. There were appointments every 10-14 days to check the setting combined with ultrasound controls. The treatment stopped if a mature, well-developed picture of both hips was seen when compared to Graf type Ia/b. Afterwards, an X-ray control was carried out at about one year of age. Results: 159 newborns with 203 dislocated hips were treated. The distribution following Graf's classification was as follows: 150 type IIc (73.9%), 18 type D (8.9%), 31 type IIIa/b (15, 3%) and 4 type IV (1.9%). To summarize, there were 150 (73.9%) type IIc hips at risk of developing a dislocation but also 53 hips (26.1%) which were already dislocated at the moment of birth. There was a loss to follow-up in three patients (1.8%), and the therapy had to be changed in six cases. There was no degradation in our study population during therapy. Conclusion: The treatment with the Pavlik harness of DDH at every stage in newborns was possible and showed good results in 189 hips.

Digital templating for the implantation of a curved short hip stem with an anterolateral MIS approach shows gender differences in digital templating.

PURPOSE: Digital templating shows reliable accuracy for straight stem systems. In recent years, the implantation of short stems through minimally invasive approaches has gained more popularity. Minimally invasive approaches (MIS) show the risk of undersizing femoral components. Therefore, we questioned the planning adherence for a curved short stem and a bi-hemispherical acetabular cup implanted through an anterolateral MIS approach. METHODS: A consecutive series of 964 hips (index surgery between 2014 and 2019) with Fitmore® curved short stem and Allofit/-S® acetabular cup (both ZimmerBiomet Inc, Warsaw, IN) were included. Preoperative digital templating was conducted anterior-posterior (AP) digital radiographs of the hip using mediCAD® version 5.1 (Hectec GmbH, Altdorf, Germany). The templates of acetabular and femoral components (offset option and stem size) were retrospectively evaluated for general adherence, and according to sex, BMI and planner's experience. RESULTS: Planning adherence for the exact offset option was 70.6 and 21.6% for exact offset option and stem size. Adherence for acetabular cup ± 1 size was 74.8%. A significant difference between male and female patients for the offset option could be found (p = 0.03, z = -2983). In 22.5% of male patients, an offset option one size higher and in 12.3% of female patients an offset option one size smaller than templated was used intraoperatively CONCLUSION: Digital templating for the Fitmore® stem in cementless THA with a minimally invasive anterolateral approach shows comparable planning adherence to the existing literature for this cementless short stem. However, a lower planning adherence was detected compared to conventional straight stem systems. In male patients, the femoral offset is frequently undersized and in female patients frequently oversized compared to the preoperative plan. Surgeons should be aware of this difficulty in digital templating for Fitmore® hip stem.

Minimally Invasive Approaching in Hip Surgery-An Anatomical Investigation of 20 Specimens.

Background and objectives: Based on the preparation of 20 formalin-fixed anatomical cadavers, the feasibility of the anterior, minimally invasive approach to the hip joint was investigated in each side of the body. The hypothesis of the study was that the Lateral Femoral Cutaneous Nerve can be spared under the use of this approach. Materials and Methods: The anterior approach to the hip was performed via an incision of 8 cm. The position of the nerve was noticed in relation to the skin incision, and the distance was measured in millimeters. The nerves main, gluteal and femoral trunk were distinguished and investigated for injury. Results: No injury of the main trunk was noticed. The average distance of the main trunk to the skin incision was 14.9 and 15.05 mm in the medial direction, respectively (p < 0.001). Injury of the gluteal branch has to be considered at an overall rate of 40%. Conclusions: The anterior, minimally invasive approach to the hip joint can be performed without injury of the Lateral Femoral Cutaneous Nerve.

Low rate of early periprosthetic fractures in cementless short-stem total hip arthroplasty using a minimally invasive anterolateral approach.

PURPOSE: Minimally invasive (MIS) approaches in combination with short stems have gained popularity in recent years in total hip arthroplasty (THA). A decreased risk for periprosthetic femoral fractures (PFFs) is reported for cementless short-stem THA, but in contrast to other approaches, the risk factors for PFFs for short-stem THA using MIS anterolateral approach in supine position are not described in literature. METHODS: A single-center consecutive series of 1052 hips in 982 patients, performed between 2014 and 2019 with a short curved stem and a press fit using an MIS anterolateral approach in supine position, was retrospectively screened for inclusion. Fourteen patients were lost to follow-up. Therefore, 1038 THAs in 968 patients were included. Risk factors for intra- and postoperative PFFs within 90 days were analyzed. We investigated for sex, age, body mass index (BMI), diagnosis, and laterality. RESULTS: In total, 18 PFFs (1.7%) occurred. Intraoperative fracture occurred in ten cases ( 0.9%), with another eight cases (0.8%) occurring postoperatively. Increased American Society of Anesthesiologists (ASA) Score was a significant risk factor for PFF (p = 0.026), whereas sex (p = 0.155), age (p = 0.161), BMI (p = 0.996), and laterality (p = 1.000) were not. Seven PFFs (0.7%) required revision arthroplasty. CONCLUSION: Cementless short-stem THA using the MIS anterolateral approach is a procedure with a low number of PFFs within 90 days from index surgery. Fracture rates are comparable to other MIS approaches, and comparable femoral short stems are used. Age, sex, and BMI were not identified as risk factors of PFF, while risk for PFF increased with ASA Score. LEVEL OF EVIDENCE: Level IV.

30-Years of experience with the cementless implanted Alloclassic CSF screw cup total hip arthroplasty system - An ultra-long-term follow-up.

OBJECTIVE: The aim of this study was to evaluate our long-term results with the Alloclassic CSF screw cup total hip arthroplasty system. This is the first study to provide a 30-year follow-up, based upon our 30-year follow up study on the Alloclassic stem system. METHODS: We reviewed 178 Alloclassic CSF screw cup systems, implanted in 171 patients from 1986 to 1987. The Zweymüller stem family was used in all cases. 136 patients had died over the last 30 years, so twenty-nine out of 35 patients being still alive, with a mean follow-up of 29,46 years (SD 0,48), were contacted by telephone and evaluated radiologically and clinically. Our loss-to-follow up was 17,14%. The mean age at follow-up was 83,01 years (72,4-95,2; SD 6,86). RESULTS: If the endpoint is defined as the removal of the cup for aseptic loosening (3 cases), the overall survival rate is 98,31%. If the endpoint is revision for any reason (27 cases), the survival rate is 84,83%. Eleven patients needed an exchange of head and liner. The mean time from implantation until change of head and liner was 21,44 years (SD 5,92). CONCLUSION: After 30 years of monitoring we can state that the evaluated system is very reliable in primary and secondary THA.

30-years of experience with the cementless implanted Alloclassic total hip arthroplasty system-An ultra-long-term follow-up.

OBJECTIVE: The aim of this study was to evaluate our long-term results with the Zweymüller hochgezogen and SL total hip arthroplasty system. This is the first study to provide a 30-year follow-up. METHODS: We reviewed 186 Alloclassic stem systems (Zweymüller hochgezogen (112) and SL (74), implanted in 179 patients from 1986 to 1987.Two different types of cementless acetabular components were used.143 patients had died over the last 30 years, so thirty out of 36 patients being still alive, with a mean follow-up of 29,48 years (SD 0,51), were contacted by telephone and evaluated radiologically and clinically. Our loss-to-follow up was 16,7%. The mean age at follow-up was 83,57 years (72,4-95,2; SD 6,77). RESULTS: If the endpoint is defined as the removal of the stem for aseptic loosening (3 cases), the overall survival rate is 98,38%. If the endpoint is revision for any reason (27 cases), the survival rate is 85,48%. Eleven patients needed an exchange of head and liner. The mean time from implantation until change of head and liner was 21,44 years (SD 5,92).Most of the radiolucent lines and osteolytic zones were found in the proximal Gruen-zones 1 and 7 (69,7 and 21,2%). CONCLUSION: After 30 years of monitoring we can state that the evaluated system is very reliable in primary and secondary THA.

Osteolysis in total hip arthroplasty after head and inlay revision surgery.

Wear debris seems to be the most likely reason for osteolysis in THA. The aim was to show the influence of head and acetabular liner revision surgery on osteolytic zones around the femoral component. Can head and inlay revision surgery reduce the size of the osteolytic zones around the femoral component? Which patients could benefit? 47 patients (51 hips), who had undergone THA head and inlay revision surgery between 1999 and 2011, were reviewed. The mean lifetime for the prosthesis was 15.1 years (8-26, standard deviation 4.5) and the mean follow-up for head and inlay was 39.2 months (12-113, standard deviation 30). The heads used in revision surgery were made of metal (26) and ceramics (25). In 36 cases a ultra-high-molecular-weight polyethylene inlay was taken, in 15 cases a regular PE-inlay. We compared the pre-surgical and follow-up anterior-posterior X-rays. The mean size of radiolucent areas before revision surgery was 147 sq.mm (5-389 sq.mm, standard deviation 115). Thirty-nine months (12-113) after surgery, their mean size was 145 sq.mm (7-604 sq.mm, standard deviation 124). Radiolucent zones exceeding 100 sq.mm could be reduced by an average of 28% in 18 out of 29 cases. The results showed an improvement in 29 out of 51 cases and a stop of progress in one case. According to the findings there may be a benefit for patients with big radiolucent areas.

Serum leptin is correlated to high turnover in osteoporosis.

OBJECTIVE: Clinical data have suggested that obesity protects against osteoporosis. Leptin, mainly secreted by white adipose tissue, might be involved by mediating an effect on bone metabolism. This study was conducted to investigate a possible relationship of leptin and bone turn-over in postmenopausal women with osteoporosis. METHODS: We measured bone mineral density (BMD), serum leptin levels and markers of bone metabolism, including osteocalcin and cross-laps in 44 patients with osteoporosis. The main group consisted of 32 postmenopausal women. RESULTS: Mean serum leptin was 13.1 microg/L and showed no statistically significant difference to the levels measured in a collective of normal persons adjusted for age and BMI. When related to serum cross-laps as markers of bone resorption, a positive correlation (p<0.05) was observed, whereas no correlation with osteocalcin could be seen. CONCLUSIONS: A dual control of bone formation by leptin is assumed: This involves local mechanisms acting on osteoblasts and a central inhibitory effect on bone metabolism via a hypothalamic relay. Our data indicate that the net effect of circulating leptin may cause bone loss and is significantly related to high-turnover serum bone markers, at least in postmenopausal women with osteoporosis.