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Periprosthetic fractures of the acetabulum represent a rare incident in primary and revision total hip arthroplasty. The management of these fractures can be challenging. At present, there are no reliable guidelines for the treatment of periprosthetic acetabular fractures. Periprosthetic acetabular fractures can occur intra-operatively, in particular during insertion of non-cemented cups or in the context of revision surgery. Post-operative causes for periprosthetic acetabular fractures are traumatic events or, more commonly, pelvic discontinuity due to severe bone loss related to osteolysis. Despite their aetiology, the main objective of surgery is to achieve a stable acetabular component and fracture. While stable fractures and implants could be treated non-operatively, unstable fractures require surgery to achieve component stability and allow appropriate biological fixation of the revision cup. Assessment of the stability plays a crucial role before determining the treatment strategy. There is a large variety of surgical techniques available for the management of these fractures. This review article outlines the epidemiology, aetiology and current classification systems, and provides a distinct diagnostic and therapeutic algorithm for the treatment of periprosthetic acetabular fractures.

Implants of microporous β-tricalcium phosphate (β-TCP) were developed for primarily stable supply of bone defects. A consistent stability over the healing period should be retained in sheep. β-TCP cylindrical shaped implants, with 7 mm diameter, 25 mm length, medium pore diameter 5 μm and 40% porosity were developed. Fresh bone defects of 21 sheep in the medial femur condyle were filled with the implants. At time zero, after 6, 12 and 24 weeks the knees of each 7 animals were studied. Specimens were investigated radiologically, followed by biomechanical and histological analysis. Radiological analysis showed progressive resorption. 6 weeks after surgery results of the indentation test were slightly lower, after 12 and 24 weeks higher than on the healthy opposite knee. At 6 weeks a phagocyte reaction overbalanced. After 12 weeks bone regeneration around the implant was seen. After 24 weeks a highly advanced resorption of TCP implant was realized. The trabecular structure of the new bone increased after 24 weeks. Using microporous β-TCP implants continuous stable filling of bone defects can be reached in sheep. Microporous β-TCP implants are resorbed and replaced by bone., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Uncemented jumbo cups are commonly used for acetabular revision because they are technically straightforward to implant and provide good intermediate-term results. Understanding long-term survival is particularly important because this method is common and because jumbo cups do not provide notable bone stock restoration. The purpose of the present study was to determine the twenty-year results of jumbo cup use during revision total hip arthroplasty. In the original publication, we reported on eighty-nine patients who underwent revision with an uncemented jumbo cup with a single design (Harris-Galante) prior to 1993. The Harris Hip Score (HHS), radiographic results, and Kaplan-Meier survivorship curves were evaluated. Mean follow-up was twenty years. The mean postoperative HHS was 71 compared with 56 preoperatively (p=0.001). A total of five jumbo cups were revised for aseptic loosening; one, for infection; and one, for recurrent dislocation. Eight liners were revised with retention of the metal acetabular component: six during femoral component revision, one for wear, and one for recurrent dislocations. Twenty-year survivorship was 88% free from aseptic loosening of the metal acetabular component, 85% free from aseptic loosening or radiographic evidence of definite loosening of the metal acetabular component, and 83% free from revision of the metal acetabular component for any reason. The twenty-year results of revision with uncemented jumbo acetabular components demonstrated acceptable clinical outcomes and radiographic stability. These results justify the use of jumbo cups as a common method of acetabular revision., (Copyright © 2015 by The Journal of Bone and Joint Surgery, Incorporated.)

Acetabular fractures increase the risk of posttraumatic arthritis and thus the risk of total hip arthroplasty (THA). We previously presented the ten-year results of THA performed for posttraumatic arthritis after an acetabular fracture; we now present the twenty-year outcomes. The original publication included sixty-six patients who underwent THA between 1970 and 1993 for posttraumatic arthritis after open reduction and internal fixation (ORIF) of an acetabular fracture. Clinical outcomes, implant survivorship, radiographic results, and complications were evaluated. A total of thirty-six patients had died. The mean Harris hip score was 80 at the latest follow-up. Nineteen acetabular and/or femoral components had been revised: eleven for aseptic loosening, seven for osteolysis, and one for instability. Twenty-year survivorship of the acetabular component was 71% free from revision for aseptic loosening and 57% free from revision for any reason. THA after ORIF of an acetabular fracture was associated with fair implant survivorship at twenty years after surgery. It is possible that newer implants with improved fixation surfaces and bearing materials may enhance long-term results, as the most common reasons for failure at twenty years were aseptic loosening and osteolysis., (Copyright © 2015 by The Journal of Bone and Joint Surgery, Incorporated.)

Background: Patient-specific instrumentation in TKA has the proposed benefits of improving coronal and sagittal alignment and rotation of the components. In contrast, the literature is inconsistent if the use of patient-specific instrumentation improves alignment in comparison to conventional instrumentation. Depending on the manufacturer, patient-specific instrumentation is based on either MRI or CT scans. However, it is unknown whether one patient-specific instrumentation approach is more accurate than the other and if there is a potential benefit in terms of reduction of duration of surgery., Questions/purposes: We compared the accuracy of MRI- and CT-based patient-specific instrumentation with conventional instrumentation and with each other in TKAs. The three approaches also were compared with respect to validated outcomes scores and duration of surgery., Methods: A randomized clinical trial was conducted in which 90 patients were enrolled and divided into three groups: CT-based, MRI-based patient-specific instrumentation, and conventional instrumentation. The groups were not different regarding age, male/female sex distribution, and BMI. In all groups, coronal and sagittal alignments were measured on postoperative standing long-leg and lateral radiographs. Component rotation was measured on CT scans. Clinical outcomes (Knee Society and WOMAC scores) were evaluated preoperatively and at a mean of 3 months postoperatively and the duration of surgery was analyzed for each patient. MRI- and CT-based patient-specific instrumentation groups were first compared with conventional instrumentation, the patient-specific instrumentation groups were compared with each other, and all three approaches were compared for clinical outcome measures and duration of surgery., Results: Compared with conventional instrumentation MRI- and CT-based patient-specific instrumentation showed higher accuracy regarding the coronal limb axis (MRI versus conventional, 1.0° [range, 0°-4°] versus 4.5° [range, 0°-8°], p < 0.001; CT versus conventional, 3.0° [range, 0°-5°] versus 4.5° [range, 0°-8°], p = 0.02), femoral rotation (MRI versus conventional, 1.0° [range, 0°-2°] versus 4.0° [range, 1°-7°], p < 0.001; CT versus conventional, 1.0° [range, 0°-2°] versus 4.0° [range, 1°-7°], p < 0.001), and tibial slope (MRI versus conventional, 1.0° [range, 0°-2°] versus 3.5° [range, 1°-7°], p < 0.001; CT versus conventional, 1.0° [range, 0°-2°] versus 3.5° [range, 1°-7°], p < 0.001), but the differences were small. Furthermore, MRI-based patient-specific instrumentation showed a smaller deviation in the postoperative coronal mechanical limb axis compared with CT-based patient-specific instrumentation (MRI versus CT, 1.0° [range, 0°-4°] versus 3.0° [range, 0°-5°], p = 0.03), while there was no difference in femoral rotation or tibial slope. Although there was a significant reduction of the duration of surgery in both patient-specific instrumentation groups in comparison to conventional instrumentation (MRI versus conventional, 58 minutes [range, 53-67 minutes] versus 76 minutes [range, 57-83 minutes], p < 0.001; CT versus conventional, 63 minutes [range, 59-69 minutes] versus 76 minutes [range, 57-83 minutes], p < .001), there were no differences in the postoperative Knee Society pain and function and WOMAC scores among the groups., Conclusions: Although this study supports that patient-specific instrumentation increased accuracy compared with conventional instrumentation and that MRI-based patient-specific instrumentation is more accurate compared with CT-based patient-specific instrumentation regarding coronal mechanical limb axis, differences are only subtle and of questionable clinical relevance. Because there are no differences in the long-term clinical outcome or survivorship yet available, the widespread use of this technique cannot be recommended.

Purpose: The aim of this study was to evaluate laxity in knees with pre-operative (preop) valgus alignment compared to knees with pre-operative varus alignment after total knee arthroplasty (TKA)., Methods: This was a retrospective study including 81 patients, with six years follow-up, for pre-operative valgus- or varus alignment of the leg. All patients had been supplied with the same cruciate retaining (CR) TKA with rotating platform. Clinical findings were assessed by KSS, OKS and IKDC 2000 score. Rotational knee laxity was evaluated by a validated instrument (Laxitester®) with 2 Nm torque in 30° flexion. Collateral ligament laxity was tested manually in 30° flexion with a bending moment of approximately 5 Nm. Biomechanical results were compared to the contralateral side., Results: Thirty-one patients had a preop valgus alignment of 8.96° and 50 patients a varus leg axis of 4.99° in the mean. In the preop valgus knees rotational analysis showed an increased laxity of 10.7° compared to preop varus knees (p = 0.001). There was no significant difference in medial (valgus 2.6 mm, varus 2.5 mm) and lateral (valgus 2.8 mm, varus 2.7 mm) laxity. KSS and OKS showed no significant differences in the follow-up results. In the IKDC 2000 objective score 50 % of the preop varus knees and 25.8 % of the preop valgus knees were classified as nearly normal. The difference in the IKDC objective was highly significant (p < 0.001)., Conclusion: Preop valgus knees show a significantly increased rotational laxity but no increased collateral ligament laxity compared to pre-operative varus knees six years after TKA with rotating platform. There is a significant difference in IKDC objective.

In the bone marrow, a population of memory T cells has been described that promotes efficient secondary immune responses and has been considered to be preactivated, owing to its expression of CD69 and CD25. Here we show that human bone marrow professional memory T cells are not activated but are resting in terms of proliferation, transcription, and mobility. They are in the G0 phase of the cell cycle, and their transcriptome is that of resting T cells. The repertoire of CD4(+) bone marrow memory T cells compared with CD4(+) memory T cells from the blood is significantly enriched for T cells specific for cytomegalovirus-pp65 (immunodominant protein), tetanus toxoid, measles, mumps, and rubella. It is not enriched for vaccinia virus and Candida albicans-MP65 (immunodominant protein), typical pathogens of skin and/or mucosa. CD4(+) memory T cells specific for measles are maintained nearly exclusively in the bone marrow. Thus, CD4(+) memory T cells from the bone marrow provide long-term memory for systemic pathogens.

Introduction: There is still a relevant rate of outliers in coronal alignment >3° when the conventional technique is used, potentially accompanied by a poorer long-term clinical outcome and a reduced longevity of the implant. Intraoperative implementation of preoperative planning and above all checking of the bone resections carried out are decisive for reinstating a straight leg axis. Intramedullary control of femoral resection has not been described to date. The objective of this study was to present a new technique for the intramedullary control of femoral resection and the results obtained using this method., Methods: All patients who underwent primary total knee arthroplasty with the new intramedullary control of femoral resection were included in this retrospective study. The frequency of the need for correction of the saw cuts was documented. The radiological assessment included pre- and postoperative whole-leg standing radiographs. In the process, the whole-leg axis, AMA, entry point, LDFA and MPTA were evaluated preoperatively. On the postoperative radiographs, the whole-leg axis and the alignment of the femoral and tibial components were evaluated., Results: One hundred and sixty-two total knee arthroplasties (TKAs) were included in the study. The average age was 68.7 years. The preoperative malalignment was on the average 8.2° ± 4.7° (23.8° varus to 17.3° valgus). The postoperative whole-leg axis was on the average 1.3° ± 1.1° (5.5° varus to 4.3° valgus). The femoral component showed a deviation from the mechanical axis of 0.1° ± 1.2° (4.3° varus to 3.7° valgus) and the tibial component a deviation from the mechanical tibial axis of 0.3° ± 1.2° (4.2° varus to 2.5° valgus)., Conclusions: The new technique of intramedullary control of distal femoral resection, together with preoperative planning, leads to a precise alignment of the femoral component in the coronal plane. Thus, for the first time, a simple and effective tool for checking distal femoral resection is available for standardized use.

Purpose: Choosing a surgical approach for total hip arthroplasty (THA) has a patient-specific impact on peri-operative muscle damage as well as postoperative functional outcome. Women and aged patients increasingly benefit from minimally invasive surgical procedures. For this reason, and due to the distinctly different bony anatomy of men and women, the hypothesis of this study is that muscle distribution around the hip joint is dependent on sex and age. The goal of this study was to analyse hip musculature in men and women and to correlate total muscle volume distribution., Methods: From 93 computed tomography (CT) scans of the pelvis (45 men, 48 women) volumes of gluteus medius (GMV), gluteus maximus (GXV) and tensor faciae latae (TFL) muscles were measured on both sides of the pelvis. The distribution of muscle volumes was normalised to patient weight and then correlated with sex and age., Results: The measured muscle volumes featured no major differences between the left and the right side. The absolute total volume of the hip-encompassing muscular system (TMV) is bigger in men than in women. Correlations between TMV and collected data were observed in both sexes in relation to body weight and size (men p < .00001; women p 0.001). With increased body weight, the TMV of the male patients increased progressively (women 11.2 cm TMV/kg KG vs. men 17.4 cm TMV/kg KG) (p 0.04). The relative distribution of each muscle volume (GMV, GXV, TFL) around the hip joint showed no major differences with respect to sex and/or age (p 0.986 and 0.996, respectively)., Conclusions: The equal relative muscle distribution in men and women around the hip joint reflects neither sex-related differences observed in clinical outcomes after THA nor bony anatomy. Yet men exhibited more muscle reserves (muscle volume; absolute and in relation to body mass) , which could explain the better outcome in men after THA. Furthermore, this suggests the extraordinary importance of muscle-sparing surgical approaches in women. The results represent the rationale for designing and analysing future studies of sex-specific therapies with regard to hip-joint muscles.

Background: Mesenchymal stem cell (MSC) therapy has the potential to enhance muscular regeneration. In previous publications, our group was able to show a dose-response relationship in female animals between the amount of transplanted cells and muscle force. The impact of sex on the regeneration of musculoskeletal injuries following MSC transplantation remains unclear., Objective: We investigated histologic and biomechanical regeneration parameters in rats after autologous transplantation of MSCs. Our hypothesis was that female rats have greater muscle regeneration potential than male rats after autologous MSC transplantation., Methods: Thirty-six Sprague-Dawley rats received an open crush trauma of the left soleus muscle. One week after trauma, 2.5 × 10(6) autologous MSCs, harvested from tibial biopsies, were transplanted locally (female, n = 9; male, n = 9). Control animals received saline solution (female, n = 9; male, n = 9). Histologic analysis and biomechanical evaluation by in vivo muscle force measurement were performed 3 weeks after transplantation., Results: MSC therapy improved the force of the injured soleus in male rats significantly (twitch: treated, 0.76 [0.51-1.15]; twitch: untreated, 0.45 [0.32-0.73] [P = 0.01]; tetany: treated, 0.63 [0.4-1.21], tetany: untreated, 0.34 [0.16-0.48] [P = 0.04]). Force measurements in females also revealed significant improvements (twitch: treated, 0.71 [0.38-0.96]; twitch: untreated, 0.36 [0.18-0.63] [P = 0.005]; tetany: treated, 0.53 [0.21-0.68]; tetany: untreated, 0.27 [0.11-0.47] [P = 0.01]). The intersexual comparison of fast twitch and tetanic contraction forces revealed no significance (twitch, P = 0.55; tetany, P = 0.19). The histologic analysis showed no differences in the amount of fibrotic tissue (male, P = 0.9; female, P = 0.14) and the size of muscle area (male, P = 0.2; female, P = 0.56) following treatment. Male animals showed higher values for muscle area (P = 0.011) and less fibrosis (P = 0.028), independent of treatment., Conclusion: The outcome of skeletal muscle regeneration after injury can be improved in animals of both sexes with MSC transplantation., (Copyright © 2012 Elsevier HS Journals, Inc. All rights reserved.)

Introduction: Skeletal muscle trauma leads to severe functional deficits, which cannot be addressed by current treatment options. Our group could show the efficacy of local transplantation of mesenchymal stroma cells (MSCs) for the treatment of injured muscles. While local application of MSCs has proven to be effective, we hypothesized that a selective intra-arterial transplantation would lead to a better distribution of the cells and so improved physiological recovery of muscle function., Materials and Methodology: 18 female Sprague Dawley rats received an open crush trauma of the left soleus muscle. Autologous MSC were transduced using dsCOP-GFP and 2.5 x 10(6)cells were transplanted into the femoral artery of 9 animals one week after trauma. Control animals (n=9) received a saline injection. Cell tracking, analysis of tissue fibrosis and muscle force measurements were performed after 3 weeks., Results: Systemic MSC-therapy improved the muscle force significantly compared to control (fast twitch: 82.4%, tetany: 61.6%, p = 0.02). The histological analysis showed no differences in the quantity of fibrotic tissue. Histological examination revealed no cells in the traumatized muscle tissue 21 days after transplantation., Conclusions: The present study demonstrated an effect of systemically administered MSCs in the treatment of skeletal muscle injuries. For possible future therapeutic approaches a systemic application of MSCs seems to present an alternative to a local administration. Such systemic treatment would be preferable since it allows functional improvement and possible cellular concentration at injury sites that are not easily accessible.

We investigated the accuracy of implant positioning during total hip arthroplasty (THA) through a minimally invasive approach in relation to body mass index (BMI) and gender by assessing 48 patients. Functional and radiological parameters were evaluated. BMI positively correlated with operation time (p=0.04), but BMI and gender had no influence on implant positioning. The Harris hip score (HHS) increased significantly (46.5 ± 11.8 preoperatively, 92.1 ± 9.7 postoperatively, p<0.0001). The surgical approach described resulted in reproducibility of implant positioning independent of influence by BMI or gender.

The volume of the gluteus medius muscle (GMV) has been shown to be closely related to hip joint function. A defined relation between joint geometry and GMV would allow a calculation of the patient-specific GMV providing reference values to individually determine the goals for rehabilitation programs after total hip arthroplasty (THA). The aim of this study was to investigate correlations between hip geometry and GMV. One hundred and two (50 female, age: 58.53 (18-86)) pelvic computed tomography (CT) scans were analyzed to determine femoral offset (FO), body weight lever arm (BWLA) and the GMV. Relationships between demographic data, FO and GMV were analyzed using correlation and regression analysis. The mean GMV was found to be 289 ± 72 cm(3), the mean FO measured was 4.14 ± 0.55 cm; and the mean value for BWLA measured was 8.88 ± 0.4 cm. A formula to calculate the GMV with a good coefficient of determination (R(2) = 0.681) (p < 0.0001) was derived. In conclusion, the formula obtained predicts individual GMV with good model fit and could be used to individually determine rehabilitation goals. Moreover, the correlation found could account for a hand in hand development of FO and GMV during growth and a continuous functional relationship thereafter., (Copyright © 2011 Elsevier Ltd. All rights reserved.)