Impact of polyethylene glenoid cementation technique on cement mantle integrity and stability after cyclic loading: a computed tomography and biomechanical study.

BACKGROUND: There are no generally accepted guidelines for polyethylene (PE) glenoid component cementation techniques. In particular, it is not known whether the backside of a PE glenoid should be fully or partially cemented-or not cemented at all. We hypothesized that cementing techniques would have an impact on cement mantle volume and integrity, as well as biomechanical stability, measured as micromotion under cyclic loading. METHODS: To address our hypothesis, 3 different cementation techniques using a single 2-peg PE glenoid design with polyurethane foam were compared regarding (1) the quality and quantity of the cement mantle and (2) biomechanical stability after cyclic loading in vitro. Eight identically cemented glenoids per group were used. Group A underwent cement application only into the peg holes, group B received additional complete cement mantle application on the backside of the glenoid, and group C received the same treatment as group B but with additional standardized drill holes in the surface of the glenoid bone for extra cement interdigitation. All glenoids underwent cyclic edge loading by 105 cycles according to ASTM F2028-14. Before and after loading, cement mantle evaluation was performed by XtremeCT and biomechanical strength and loosening were evaluated by measuring the relative motion of the implants. RESULTS: The cement mantle at the back of the implant was incomplete in group A as compared with groups B and C, in which the complete PE backside was covered with a homogeneous cement mantle. The cement mantle was thickest in group C, followed by group B (P = .006) and group A (P < .001). We did not detect any breakage of the cement mantle in any of the 3 groups after testing. Primary stability during cyclic loading was similar in all groups after the "running-in" phase (up to 4000 cycles). Gross loosening did not occur in any implant. CONCLUSIONS: Coverage of the PE glenoid with cement was reproducible in the fully cemented groups (ie, groups B and C) as compared with relevant cement defects in group A. The addition of cement to the back of the PE glenoid and additional drill holes in the glenoid surface did not improve primary stability in the tested setting.

Evaluation of a New Exercise Program in the Treatment of Scapular Dyskinesis.

An abnormal motion of the scapula, or scapular dyskinesis (SD), can be effectively treated through conservative therapy. The aim of this study is to evaluate a new specific exercise program to restore normal position. A standardized and specific exercise program was created. In a prospective multi-center approach, patients were randomized into two groups: one group received the specific exercise program over a period of six weeks and the controls received massage therapy. The visual-analog scale, QuickDASH score, SICK scapula rating scale, hand press-up position test, lateral scapular slide test and internal rotation of the shoulder were evaluated. Twenty-eight patients were included in the study: fifteen in the exercise group and thirteen in the control group. Pain levels on the visual analog scale (VAS) were significantly reduced in both groups (exercise p=0.007; control p=0.004). The scores for QuickDASH (p=0.001), SICK scapula rating scale (p=0.003) and hand press-up position test (p=0.026) were significantly improved in the exercise group only. Scapula-focused exercise programs, as well as massage therapy, can effectively relieve pain in patients with SD. However, scapula-focused exercises resulted, specifically, in greater improvement of shoulder function.

Influence of scapular tilt on radiographic assessment of the glenoid component after total shoulder arthroplasty: which radiographic landmarks are reliable?

BACKGROUND: Total shoulder arthroplasty has been shown to improve function and to reduce pain in cases of osteoarthritis. To assess loosening of the glenoid component, serial evaluation of frontal plane radiographs of the scapula has been established as the "gold standard." The aim of this study was to evaluate the reliability of different bone landmarks when the scapula is tilted compared with the ideal view. METHODS: Glenoid components were implanted into 6 human cadaveric scapulae. Radiographs were taken exactly anterior-posterior in the frontal plane as well as craniocaudal tilted (±15° and ±30°) and mediolateral tilted (±10° and ±20°). The following landmarks were evaluated: lateral margin of the scapula, medial margin of the scapula, floor of the fossa supraspinatus line, spine of the scapula line, glenoid fossa line, and coracoid base line. RESULTS: In evaluating the inclination of the glenoid component, the medial margin of the scapula had the best intraobserver and interobserver reliability with a variance for each of 2° ± 1° (P < .0001), whereas the lateral margin of the scapula had an acceptable intraobserver and interobserver reliability with a variance of 4° ± 1° and 3° ± 1°. In measuring medial migration, the glenoid fossa line had a significantly lower intraobserver and interobserver reliability than the coracoid base line (each 1 ± 0 mm vs. 3 ± 1 mm and 3 ± 2 mm; P < .0001). CONCLUSION: To assess the inclination of the glenoid component, the medial margin of the scapula has proven best, and the lateral margin of the scapula has acceptable reliability. For measuring medial migration, the coracoid base line has proven acceptable reliability, whereas the glenoid fossa line would be subject to change when osteolysis occurs at the glenoid.

Motion patterns in activities of daily living: 3- year longitudinal follow-up after total shoulder arthroplasty using an optical 3D motion analysis system.

BACKGROUND: Total shoulder arthroplasty (TSA) can improve function in osteoarthritic shoulders, but the ability to perform activities of daily living (ADLs) can still remain impaired. Routinely, shoulder surgeons measure range of motion (ROM) using a goniometer. Objective data are limited, however, concerning functional three-dimensional changes in ROM in ADLs after TSA in patients with degenerative glenohumeral osteoarthritis. METHODS: This study included ten consecutive patients, who received TSA for primary glenohumeral osteoarthritis. The patients were examined the day before, 6 months, and 3 years after shoulder replacement as well. We compared them with a control group (n = 10) without any shoulder pathology and measured shoulder movement by 3D motion analysis using a novel 3 D model. The measurement included static maximum values, the ability to perform and the ROM of the ADLs "combing the hair", "washing the opposite armpit", "tying an apron", and "taking a book from a shelf". RESULTS: Six months after surgery, almost all TSA patients were able to perform the four ADLs (3 out of 40 tasks could not be performed by the 10 patients); 3 years postoperatively all patients were able to carry out all ADLs (40 out of 40 tasks possible). In performing the ADLs, comparison of the pre- with the 6-month and 3-year postoperative status of the TSA group showed that the subjects did not fully use the available maximum flexion/extension ROM in performing the four ADLs. The ROM used for flexion/extension did not change significantly (preoperatively 135°-0° -34° vs. 3 years postoperatively 131° -0° -53°). For abduction/adduction, ROM improved significantly from 33°-0° -27° preoperatively to 76° -0° -35° postoperatively. Compared to the controls (118°) the TSA group used less ROM for abduction to perform the four ADLs 3 years postoperatively. CONCLUSION: TSA improves the ability to perform ADL and the individual ROM in ADLs in patients with degenerative glenohumeral osteoarthritis over the course of 3 years. However, TSA patients do not use their maximum available abduction ROM in performing ADLs. This is not related to limitations in active ROM, but rather may be caused by pathologic motion patterns, impaired proprioception or both.

An epidemiological investigation of training and injury patterns in triathletes.

Associated with the trend towards increased health consciousness and fitness, triathlon has established itself as a sport for masses. The goals of this study were to evaluate injury risk factors of non-professional triathletes and to compare prospective and retrospective evaluation methods. Using an online survey, 212 triathletes retrospectively answered a questionnaire about their training habits and injuries during the past 12 months. Forty-nine of these triathletes participated in a 12-month prospective trial. Injuries were classified with regard to the anatomical location, type of injury, incidence and associated risk factors. Most injuries occurred during running (50%) followed by cycling (43%) and swimming (7%). Fifty-four per cent (retrospective) and 22% (prospective) of the injuries were contusions and abrasions, 38% (retrospective) and 46% (prospective) were ligament and capsular injuries, 7% (retrospective) and 32% (prospective) were muscle and tendon injuries and 1% (retrospective) and 0% (prospective) were fractures. The incidence of an injury per 1000 training hours was 0.69 (retrospective) and 1.39 (prospective) during training and 9.24 (retrospective) and 18.45 (prospective) during competition. The main risk factor for injury in non-professional triathlon is participation in a competitive triathlon event. A retrospective design may underestimate the rate of overuse injuries.

How does reverse shoulder replacement change the range of motion in activities of daily living in patients with cuff tear arthropathy? A prospective optical 3D motion analysis study.

BACKGROUND: Reverse total shoulder arthroplasty (RSA) can improve function in cuff tear arthropathy (CTA) shoulders, but limited exact data are available about the maximum values in 3D motion analysis, and as to how improvements translate into the normal range of motion (ROM) in activities of daily living (ADLs). METHODS: This study included nine consecutive patients (n = 9) who received RSA for CTA without muscle transfers. We measured shoulder movement by a novel 3D motion analysis using the Heidelberg upper extremity model (HUX) which can eliminate compensatory movements of the scapula, and the trunk. The measurement included active maximum values, and four ADLs. RESULTS: Comparing the pre- to the 1-year postoperative status, RSA was associated with a significant increase in the mean maximum values for active flexion of about 43° (SD ± 31) from 66° to 109° (p = 0.001), for active abduction of about 37° (SD ± 26) from 57° to 94° (p = 0.001), and for the active adduction of about 28° (SD ± 10) from 5° to 33° (p = 0.002). Comparing the preoperative to the postoperative ROM in the ADLs in flexion/extension, ROM improved significantly in all ADLs, in abduction/adduction in three of four ADLs. No significant changes were observed in internal/external rotation in any ADLs. CONCLUSION: RSA improves the active maximum ROM for flexion, abduction, and adduction. The patients are able to take advantage of this ROM increase in ADLs in flexion and in most ADL in abduction, but only in trend in internal and external rotation.

Bilateral idiopathic osteonecrosis of the major tubercle of the humerus.

UNLABELLED: Bilateral osteonecrosis of the tuberculum majus has not been reported in the literature. A case of bilateral avascular necrosis of the tuberculum majus is presented associated with smoking and occasional alcohol consumption as risk factors, which was successfully treated with non-operative treatment. LEVEL OF EVIDENCE: Case report, Level V.

Etiology, Classification, Diagnostics, and Conservative Management of Osteochondral Lesions of the Talus. 2023 Recommendations of the Working Group "Clinical Tissue Regeneration" of the German Society of Orthopedics and Traumatology.

METHODS: Peer-reviewed literature was analyzed regarding different topics relevant to osteochondral lesions of the talus (OLTs) treatment. This process concluded with a statement for each topic reflecting the best scientific evidence available for a particular diagnostic or therapeutic concept, including the grade of recommendation. Besides the scientific evidence, all group members rated the statements to identify possible gaps between literature and current clinical practice. CONCLUSION: In patients with minimal symptoms, OLT progression to ankle osteoarthritis is unlikely. Risk factors for progression are the depth of the lesion on MRI, subchondral cyst formation, and the extent of bone marrow edema. Conservative management is the adaptation of activities to the performance of the ankle joint. A follow-up imaging after 12 months helps not to miss any progression. It is impossible to estimate the probability of success of conservative management from initial symptoms and imaging. Cast immobilization is an option in OLTs in children, with a success rate of approximately 50%, although complete healing, estimated from imaging, is rare. In adults, improvement by conservative management ranges between 45% and 59%. Rest and restrictions for sports activities seem to be more successful than immobilization. Intra-articular injections of hyaluronic acid and platelet-rich plasma can improve pain and functional scores for more than 6 months. If 3 months of conservative management does not improve symptoms, surgery can be recommended.

Proprioception 3 years after shoulder arthroplasty in 3D motion analysis: a prospective study.

BACKGROUND: This prospective study evaluated the development of proprioception over the course of 3 years after shoulder arthroplasty. METHODS: Twenty-one patients were enrolled who underwent total shoulder arthroplasty (n = 10) or hemiarthroplasty (HEMI) (n = 11) for shoulder osteoarthritis. All patients were examined 1 day before the operation, 6 months and 3 years after surgery in a motion analysis study with an active angle-reproduction (AAR) test. RESULTS: Overall proprioception measured by the AAR deteriorated significantly 3 years after surgery [from 6.6° (SD 3.1) to 10.3° (SD 5.7); p = 0.017] and was significantly worse than in the control group [10.3° (SD 5.7) vs. 7.8° (SD 2.3); p = 0.030). In the HEMI subgroup, 3 years after shoulder replacement, there is a significant deterioration of proprioception at 30° of external rotation [from 3.1° (SD 3.5) to 12.8° (SD 10.7); p = 0.031]. On average, in the TSA subgroup proprioception deteriorated from 7.1° (SD 3.1) to 8.6° (SD 1.4) and in the HEMI subgroup from 6.1° (SD 2.1) to 12.4° (SD 8.3). The comparison of postoperative impairment of proprioception between the TSA and HEMI subgroup showed significantly worse proprioception for the HEMI subgroup at 30° of external rotation [9.8° (SD 10.1) vs. 1.6° (SD 6.3) in the TSA group; p = 0.046]. CONCLUSION: In conclusion, proprioception that was measured by an AAR test remained unchanged or deteriorated 3 years after shoulder arthroplasty. The postoperative deterioration of proprioception was more distinctive in HEMI than in TSA group.

Subcutaneous emphysema of the upper extremity after elbow arthroscopy.

Subcutaneous emphysema of the upper extremity is rare. Crepitation on physical examination and visible gas on radiographs raise the concern of gas gangrene due to gas-producing bacteria. Rapid establishment of a differential diagnosis is necessary to initiate proper treatment. We present a case of subcutaneous emphysema after elbow arthroscopy caused by a noninfectious genesis. A 59-year-old woman with loose bodies in her left elbow due to mild degenerative joint disease and restricted range of motion was offered an elbow arthroscopy with removal of loose bodies and arthrolysis. Postoperatively, the elbow was actively put alternatively in maximum extension and flexion. On the first postoperative day, rapidly ascending swelling and subcutaneous crepitation starting from the hand to the forearm were noted. There was no clinical evidence of infection. Radiographs showed subcutaneous air. Frequent blood tests and clinical evaluation ruled out a potentially life-threatening bacterial infection, and the signs resolved after 1 week without surgical treatment. Presumably, the intensive postoperative range-of-motion exercises led to a sucking in of air into the wound during each movement. This case illustrates that it is important to differentiate nonbacterial from bacterial causes of soft-tissue gas formation to initiate the appropriate treatment.

Prospective randomised comparison of arthroscopic versus mini-open rotator cuff repair of the supraspinatus tendon.

PURPOSE: The aim of the study was to evaluate whether arthroscopic (ASC) repair of rotator cuff ruptures causes less postoperative pain and better range of motion (ROM) in the early postoperative period than a mini-open (MO) technique. METHODS: Inclusion criteria were a rupture of the supraspinatus tendon with retraction with a maximum to the apex of the humeral head and minor fatty degeneration and atrophy of the muscle. Each group (n = 17) had similar demographics and preoperative magnetic resonance imaging (MRI) findings (mean age 60.1 years, SD 8.8, range 43-71). The ASC group underwent double-row repair with resorbable anchors; the MO group received a transosseous repair. The postoperative rehabilitation was standardised and equivalent in both groups. RESULTS: In the first week fewer nonsteroidal anti-inflammatory drug (NSAID) tablets were needed in the ASC group. Pain scores on the visual analogue scale were similar in the first three weeks; however, from week four to eight the MO group had less pain (p < 0.05). After six months, the Constant-Murley score and the ROM improved significantly (p < 0.05) in both groups without differences between the groups. Postoperative MRI revealed in three of 16 patients a discontinuity of the tendon in both groups; in the ASC group there were more patients (n = 9) with a thinning of the tendon compared to the MO group (n = 6). CONCLUSIONS: There was less use of NSAIDs in the first postoperative week in the ASC group, indirectly indicating less pain, but higher pain scores in the later course (weeks four to eight) compared to the MO group. ROM, MRI findings and the scores were similar after six months, demonstrating that both techniques are equivalent regarding the outcome in this period.

Cement pressurizing reduces radiolucent lines at glenoid: A randomized, multicentric study.

BACKGROUND: The hypothesis of this study is that cement pressurization into the glenoid reduces the rate of radiolucent lines in total shoulder arthroplasty in the mean 25.5 months after the operation. METHODS: To examine this effect, a multicentric prospective randomized study (level of evidence 1) was initiated: one group (group P, n = 24) received intraoperative pressurization of cement into the cancellous bone of the glenoid, the other cement without pressure (group NoP, n = 27). Inclusion criteria were an osteoarthritis with glenoid erosion <15° and an intact rotator cuff. RESULTS: There were no significant differences preoperatively between the groups regarding age (mean age 66 ± 10 years (range 44-81)), gender, range of motion, scores and pathomorphology. Both groups had a significant improvement of the scores, strength, motion and satisfaction 25.5 months after the intervention. The scores were similar between the groups (ns). However, cement pressurization at the glenoid side significantly reduced the incidence of radiolucent lines (p < 0.027). CONCLUSION: This supports the use of this simple technique to improve long-term survival of total shoulder arthroplasty.Level of evidence: 1.

Enhanced ITM2A expression inhibits chondrogenic differentiation of mesenchymal stem cells.

Mesenchymal stem cells (MSC) from bone marrow or adipose tissue (ASC) are broadly discussed as a cell population able to support cartilage regeneration and thus represent interesting candidates for cell-based tissue engineering in cartilage. ASC could represent an easily accessible and therefore particularly suitable source of cells. Their chondrogenic differentiation potential is, however, lower than that of MSC. The aim of this work was to characterise ASC in comparison to MSC in order to identify genes which may be involved in mechanisms causing the altered chondrogenic potential of ASC. Representational difference analysis was used to identify genes with higher expression in undifferentiated ASC than in MSC. Expression levels of identified genes were confirmed by real-time RT-PCR. Integral membrane protein 2A (ITM2A) was higher expressed in expanded ASC than in MSC in a donor-independent manner. During early chondrogenic differentiation in spheroid cultures ITM2A levels remained low in MSC and a transient down-regulation occurred in ASC correlating with successful chondrogenesis. Persisting ITM2A levels were found in non-differentiating ASC. Consistent with this finding, forced expression of ITM2A in the mouse mesenchymal stem cell line C3H10T1/2 prevented chondrogenic induction. In conclusion, ITM2A may in early stages of differentiation be associated with an inhibition of the initiation of chondrogenesis and elevated expression of ITM2A in ASC may therefore be linked to the poorer chondrogenic differentiation potential of these cells.

What is the role of intra-operative fluoroscopic measurements to determine tibial tunnel placement in anatomical anterior cruciate ligament reconstruction?

The hypothesis for this study was that intra-operative fluoroscopic measurements can be used to determine tibial tunnel placement during anatomic anterior cruciate ligament (ACL) reconstruction. The anteromedial (AM) and posterolateral (PL) bundle insertion sites were marked with a thermal device and measured in a consecutive cohort of 67 patients undergoing anatomical ACL reconstruction. For double bundle reconstruction, guide pins were passed in the center of the AM and PL tibial footprints. For single bundle (SB) reconstruction a guide wire was placed between the center of AM and PL footprints. Subsequently, the position of the centers of the AM and PL insertion sites were measured on standardized lateral intra-operative fluoroscopic images. The center for the AM bundle was found to be at 31% (range 20-42%) of the AP distance on the medial joint line and at 35% (range 23-42%) of the AP distance on the Amis and Jakob line. The center of the PL bundle was at 48% (range 37-59%) of the AP distance on the medial joint line and 48% (range 39-58%) of the AP distance on the Amis and Jakob line. The center of the tibial tunnel in the SB group (n = 15) was at 42 and 41% in relation to the medial joint line and the Amis and Jakob line, respectively. Because a significant anatomic variation exists between patients, the decision with respect to tunnel placement should not be merely based on intra-operative fluoroscopic images.

Can shoulder arthroplasty restore the range of motion in activities of daily living? A prospective 3D video motion analysis study.

HYPOTHESIS: There are limited data how total shoulder arthroplasty (TSA) improves shoulder function during activities of daily living (ADL). The hypothesis of this study was that the range of motion (ROM) in ADL gets back to normal after TSA. MATERIALS AND METHOD: We examined 13 patients before they received TSA for osteoarthritis and 6 months postoperatively with a 3D motion video analysis during 3 ADL and compared them with a control group without any shoulder pathology. RESULT: Comparing the TSA status preoperatively and postoperatively resulted in a significant increase of the mean values of the ROMs in the ADL in all planes (P < .05). When the postoperative ROM was compared with the controls, TSA was able to restore the ROM in all planes except for abduction in 2 of 3 ADL. The patients were not able to use their maximum active abduction during the course of the ADL. DISCUSSION: TSA improves the ROM in ADL, but it cannot return completely to normal in abduction after 6 months. CONCLUSION: This is not related to limitations of active or passive ROM but may be due to impaired proprioception or pathologic movement patterns, or both.

Three-dimensional motion analysis of compensatory movements in patients with radioulnar synostosis performing activities of daily living.

BACKGROUND: The aim of this study was to quantify the compensatory movements of the shoulder and elbow in patients with congenital radioulnar synostosis during 10 activities of daily living (ADL). METHODS: Maximum and minimum joint angles and range of motion were measured by use of a motion capture system in seven patients and seven matched controls. The forearm was fixed in 0 degrees of rotation in four patients and in 20 degrees of pronation in three patients. RESULTS: The main compensatory movements were shoulder internal/external rotation during five ADL tasks, shoulder abduction/adduction and elbow flexion/extension during three tasks, and shoulder flexion/extension during two tasks. These compensatory movements were observed mainly when turning a key and drawing. CONCLUSIONS: Patients with congenital radioulnar synostosis in nearly neutral rotation could perform all ADL tasks with the aid of compensatory movements of the shoulder and elbow.

Myoelectric hand prostheses in very young children.

Myoelectric prostheses have generally been provided for adolescent or adult patients. The availability of smaller-sized electric hands has enabled the introduction of myoelectric prostheses to preschool children, mainly in the Scandinavian countries. This study evaluates the acceptance of myoelectric prostheses in 41 children with unilateral upper limb deficiency between the ages of two and five years. The prosthesis was used for an average time of 5.8 hours per day. The level of amputation was found to influence the acceptance rate. Furthermore, prosthetic use training by an occupational therapist is related to successful use of the prosthesis. The general drop-out rate in preschool children is very low compared to adults. Therefore, infants can profit from myoelectric hand prostheses. Since a correct indication and an intense training program significantly influence the acceptance rate, introduction of myoelectric prostheses to preschool children should take place at specialised centres with an interdisciplinary team.

Proprioception in total, hemi- and reverse shoulder arthroplasty in 3D motion analyses: a prospective study.

The aim of the study was to assess proprioception after shoulder arthroplasty. Twenty-six patients were enrolled who underwent total shoulder arthroplasty (TSA) (n = 13) or hemi-arthroplasty (n = 8) for shoulder osteoarthritis or reversed arthroplasty (n = 5) for cuff tear arthropathy. All patients were examined before the operation and then again six months thereafter in a motion analysis study with an active angle-reproduction (AAR) test. In all groups the AAR deteriorated at 60 degrees flexion (from 5.5 degrees [SD 2.8] to 7.6 degrees [SD 2.7]; p = 0.007) and at 30 degrees external rotation (ER) (from 6.5 degrees [SD 3.6] to 7.3 degrees [SD 4.8 degrees]; p = 0.023) six months after surgery. In the subgroup of TSA, there was deterioration at 30 degrees ER (p = 0.036). Otherwise, there were no significant changes within or among the subgroups. Proprioception, assessed by the AAR test, remained unchanged or deteriorated six months after shoulder arthroplasty. This might be related to the reduced pain or to the relatively short follow-up period.

Instability of the proximal radioulnar joint in Monteggia fractures-an experimental study.

BACKGROUND: A Monteggia fracture is defined as a fracture of the proximal ulna combined with a luxation of the radial head. The aim of the present work is to evaluate the extent of instability of the radius head in the proximal radioulnar joint (PRUJ) as a function of the severity of elbow fracture and ligamentous injury in an experimental biomechanical approach. METHODS: Eight fresh-frozen cadaver arms were used. All soft tissues were removed except for the ligamentous structures of the PRUJ and forearm. A tensile force of 40 N was exerted laterally, anteriorly or posteriorly onto the proximal radius. The dislocation in the PRUJ was photometrically recorded and measured by two independent examiners. After manual dissection of the ligamentous structures up to the interosseous membrane, the instability was documented and subsequently measured. The following dissection levels were differentiated: intact ligamentous structures, dissection of annular ligament, oblique cord and proximal third of interosseous membrane. RESULTS: An anterior instability remains relatively constant until the proximal third of the interosseous membrane is dissected. The radial head already dislocates relevantly in the posterior direction after dissection of the annular ligament with an additional considerable stability anteriorly and laterally. Subsequently, the posterior instability increases less pronouncedly in regard of distal resected structures. The lateral instability increases constantly during the progressing resection of the ligamentous structures. CONCLUSION: On the one hand, a complete healing of the ligament injury after functional treatment is hardly conceivable with ligamentary damage up to the level of the proximal interosseous membrane. A remaining instability of the proximal radius could therefore be a possible cause for the unsatisfactory clinical results after certain Monteggia fractures. On the other hand, the present study may give a possible explanation (i.e. early dorsal radius head dislocation after dissection of annular ligament) why the Bado II injury is the most frequent type of Monteggia fractures.

Two-step stem cell therapy improves bone regeneration compared to concentrated bone marrow therapy.

Adult stem cells are a promising tool to positively influence bone regeneration. Concentrated bone marrow therapy entails isolating osteoprogenitor cells during surgery with, however, only low cells yield. Two step stem cell therapy requires an additional harvesting procedure but generates high numbers of progenitor cells that facilitate osteogenic pre-differentiation. To further improve bone regeneration, stem cell therapy can be combined with growth factors from platelet rich plasma (PRP) or its lysate (PL) to potentially fostering vascularization. The aim of this study was to investigate the effects of bone marrow concentrate (BMC), osteogenic pre-differentiation of mesenchymal stromal cells (MSCs), and PL on bone regeneration and vascularization. Bone marrow from four different healthy human donors was used for either generation of BMC or for isolation of MSCs. Seventy-two mice were randomized to six groups (Control, PL, BMC, BMC + PL, pre-differentiated MSCs, pre-differentiated MSCs + PL). The influence of PL, BMC, and pre-differentiated MSCs was investigated systematically in a 2 mm femoral bone defect model. After a 6-week follow-up, the pre-differentiated MSCs + PL group showed the highest bone volume, highest grade of histological defect healing and highest number of bridged defects with measurable biomechanical stiffness. Using expanded and osteogenically pre-differentiated MSCs for treatment of a critical-size bone defect was favorable with regards to bone regeneration compared to treatment with cells from BMC. The addition of PL alone had no significant influence; therefore the role of PL for bone regeneration remains unclear. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1318-1328, 2019.