A neck-sparing short stem shows significantly lower blood loss in total hip arthroplasty compared to a neck-resecting short stem.

Short stems are associated with a significantly lower blood loss (BL) compared to straight stems in total hip arthroplasty (THA). Different types of stems differ in design, fixation and level of femoral neck osteotomy. Therefore, we sought to evaluate the difference regarding the perioperative BL between two short stems with different designs in direct anterior approach (DAA). A total of 187 THA performed by a single surgeon were analysed. 107 patients received a neck-resecting (Group A) and 80 patients a neck-sparing short stem (Group B). Blood counts of the day before surgery and of two days after surgery were evaluated. Total blood volume and BL were calculated. Additionally, duration of surgery was analysed. The perioperative BL was significantly lower in Group B (451.4 ± 188.4 ml) compared to Group A (546.6 ± 232.7 ml; p = 0.002). The postoperative haematocrit (31.6 ± 3.7% vs. 30.4 ± 4.4%; p = 0.049) and haemoglobin-level (11.0 ± 1.3 g/dL vs. 10.4 ± 1.5 g/dL; p = 0.002) were significantly higher in Group B. Duration of surgery was significantly shorter in Group B (62.0 ± 11.4 min vs. 72.6 ± 21.8 min; p < 0.001). The use of a neck-sparing short stem leads to a significantly decreased BL compared to a neck-resecting short stem in DAA THA. A less extensively conducted capsular release necessary for optimal femoral exposition might lead to a lower perioperative BL and shorter durations of surgery.

Digital templating cementless short stem total hip arthroplasty: is there a difference in planning adherence between the direct anterior approach and minimally invasive anterolateral approach?

PURPOSE: Minimally invasive approaches (MIS) in total hip arthroplasty (THA) show inconsistent findings regarding planning adherence in digital templating. The purpose of this study is to evaluate any difference in planning adherence between the direct anterior approach (DAA) and an anterolateral MIS approach (AL MIS) in cementless short stem THA. METHODS: A single surgeon series of 222 THAs in 208 patients with an uncemented short curved stem and a bi-hemispherical acetabular cup were screened for inclusion. A total of 118 THAs were implanted via the DAA and 72 THAs via the AL MIS were included. The planning adherence for the offset option, stem size and the acetabular cup were retrospectively evaluated. RESULTS: Planning adherence for cup size (perfect match: p = 0.763; ± 1 size: p = 0.124), offset option (0.125) and stem size (perfect match: p = 0.275; ± 1 size: p = 0.552) did not show any statistical significance. Preoperative diagnosis of avascular necrosis of the femoral head in AL MIS approach (OR 6.045; CI 1.153-31.696) or mild hip dysplasia in the general cohort poses (OR 11.789; CI 1.386-100.293) a significant risk for inadequate prediction of the offset option. CONCLUSION: digital templating for THA with an uncemented short curved stem and a bi-hemispherical acetabular cup show comparable results between a direct anterior approach and a minimally invasive anterolateral approach in supine position. Surgeons should be aware of a low planning adherence for this type of short stem in minimally invasive approaches. CONCLUSION: Digital templating for THA with an uncemented short curved stem and a bi-hemispherical acetabular cup show comparable results between a direct anterior approach and a minimally invasive anterolateral approach in supine position. Surgeons should be aware of a low planning adherence for this type of short stem in minimally invasive approaches.

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.

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.

A single-surgeon experience in reconstruction of femoro-acetabular offset and implant positioning in direct anterior approach and anterolateral MIS approach with a curved short stem.

PURPOSE: Minimally invasive surgery using short stems in total hip arthroplasty gained more popularity. The differences in change of hip offset and implant positioning in minimally invasive approaches are not fully known. Therefore, this study was conducted to evaluate the difference in reconstruction of hip offset and implant positioning in direct anterior approach (DAA) and minimally invasive anterolateral approach (AL MIS). METHODS: A single surgeon series of 117 hips (117 patients; mean age 65.54 years ± 11.47; index surgery 2014-2018) were included and allocated into two groups: group A (DAA) with 70 hips and Group B (AL MIS) with 47 patients operated. In both groups the same type of cementless curved short hip stem and press fit cup was used. RESULTS: Both groups showed an equal statistically significant increase of femoral (p < 0.001) and decrease of acetabular offset (p < 0.001). Between both groups no statistically significant difference in offset reconstruction, leg length difference or implant positioning could be found. Leg length increased in both groups significantly and leg length discrepancy showed no difference (group A: - 0.06 mm; group B: 1.11 mm; p < 0.001). A comparable number of cups were positioned outside the target zone regarding cup anteversion. CONCLUSION: The usage of a curved short stem shows an equal reconstruction of femoro-acetabular offset, leg length and implant positioning in both MIS approaches. The results of this study show comparable results to the existing literature regarding change of offset and restoration of leg length. Malposition of the acetabular component regarding anteversion poses a risk.

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.

Obesity in short stem total hip arthroplasty using a minimally invasive supine anterolateral approach-a risk factor for short-term complications?

PURPOSE: Obesity is associated with increased risk for surgical complications in total hip arthroplasty (THA). The impact of obesity on short-term complication in minimally invasive (MIS) anterolateral approach is not well known. Therefore, this study was conducted to evaluate the early complications within the first 90 days after THA using a MIS anterolateral approach with a short-curved stem stratified by Body Mass Index (BMI). PATIENTS AND METHODS: A single centre consecutive series of 1052 hips in 982 patients (index surgery 2014-2019) with a short-curved stem and press fit cup implanted using a MIS anterolateral approach in supine position were screened for inclusion. Inclusion criteria were defined as end-stage primary osteoarthritis of the hip. Eventually, 878 implantations in 808 patients were included and stratified by body mass index (BMI). Peri-operative complications, within the first 90 days after surgery, were retrospectively evaluated. RESULTS: Severely obese patients (BMI ≥ 35 kg/m2) and morbidly obese patients (BMI ≥ 40 kg/m2) demonstrated a significantly increased operation time (p < 0.001) and a higher risk for general surgical complications (p = 0.015) (odds ratio (OR) = 4.365; OR = 4.985), periprosthetic joint infection (PJI) (p = 0.001) (OR = 21.687; OR = 57.653), and revision (OR = 8.793; OR = 20.708). CONCLUSION: The risk for early PJI and overall surgical complications in MIS anterolateral approach is significantly increased in severely and morbidly obese patients. This leads to a significantly higher risk for revision surgery after index surgery within the first 90 days. A BMI above 35 kg/m2 is the clear threshold for increased risk of PJI in MIS anterolateral THA with a short curved stem. As the surgical complications are comparable to other approaches, MIS anterolateral short stem THA is also feasible with increasing BMI.

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.

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.