Georg Osterhoff

Matrix-Associated Implantation of Predifferentiated Mesenchymal Stem Cells Versus Articular Chondrocytes: In Vivo Results of Cartilage Repair After 1 Year

Background: The use of predifferentiated mesenchymal stem cells (MSC) leads to better histological results compared with undifferentiated MSC in sheep. This raises the need for a longer term follow-up study and comparison with a clinically established method. Hypothesis: We hypothesized that chondrogenic in vitro predifferentiation of autologous MSC embedded in a collagen I hydrogel leads to better structural repair of a chronic osteochondral defect in an ovine stifle joint after 1 year. We further hypothesized that resulting histological results would be comparable with those of chondrocyte-seeded matrix-associated autologous chondrocyte transplantation (MACT). Study Design: Controlled laboratory study. Methods: Predifferentiation period of ovine MSC within collagen gel in vitro was defined by assessment of several cellular and molecular biological parameters. For the animal study, 2 osteochondral lesions (7-mm diameter) were created at the medial femoral condyles of the hind legs in 9 sheep. Implantation of MSC gels was performed 6 weeks after defect creation. Thirty-six defects were divided into 4 treatment groups: (1) chondrogenically predifferentiated MSC gels (pre-MSC gels), (2) undifferentiated MSC gels (un-MSC gels), (3) MACT gels, and (4) untreated controls (UC). Histological, immunohistochemical, and radiological evaluations followed after 12 months. Results: After 12 months in vivo, pre-MSC gels showed significantly better histological outcome compared with un-MSC gels and UC. Compared with MACT gels, the overall scores were higher for O’Driscoll and International Cartilage Repair Society (ICRS). The repair tissue of the pre-MSC group showed immunohistochemical detection of interzonal collagen type II staining. Radiological evaluation supported superior bonding of pre-MSC gels to perilesional native cartilage. Compared with previous work by our group, no degradation of the repair tissue between 6 and 12 months in vivo, particularly in pre-MSC gels, was observed. Conclusion: Repair of chronic osteochondral defects with collagen hydrogels composed of chondrogenically predifferentiated MSC shows no signs of degradation after 1 year in vivo. In addition, pre-MSC gels lead to partially superior histological results compared with articular chondrocytes. Clinical Relevance: The results suggest an encouraging method for future treatment of focal osteochondral defects without donor site morbidity by harvesting articular chondrocytes.

Medial support by fibula bone graft in angular stable plate fixation of proximal humeral fractures: an in vitro study with synthetic bone

BACKGROUND Failure to achieve stable fixation with medial support in proximal humeral fractures can result in varus malalignment and cut-through of the proximal screws. The purpose of this study was to investigate the influence of an intramedullary fibula bone graft on the biomechanical properties of proximal humeral fractures stabilized by angular stable plate fixation in a bone model under cyclic loading. METHODS Two fixation techniques were tested in 20 composite analog humeri models. In group F- (n = 10), fractures were fixed by an anatomically formed locking plate system. In group F+ (n = 10), the same fixation system was used with an additional fibular graft model with a length of 6 cm inserted in an intramedullary manner. Active abduction was simulated for 400 cycles by use of a recently established testing setup. Fragment gap distance was measured, and thereby, intercyclic motion, fragment migration, and residual plastic deformation were determined. RESULTS The addition of a fibular graft to the fixation plate led to 5 times lower intercyclic motion, 2 times lower fragment migration, and 2 times less residual plastic deformation. Neither screw pullout, cut-through, nor implant failure was observed. CONCLUSION Medial support with an intramedullary fibular graft in an angular stable fixation of the proximal humerus in vitro increases overall stiffness of the bone-implant construct and reduces migration of the humeral head fragment. This technique might provide a useful tool in the treatment of displaced proximal humeral fractures, especially when there is medial comminution.

Autologous chondrocyte implantation (ACI) for the treatment of large and complex cartilage lesions of the knee

BackgroundComplex cartilage lesions of the knee including large cartilage defects, kissing lesions, and osteoarthritis (OA) represent a common problem in orthopaedic surgery and a challenging task for the orthopaedic surgeon. As there is only limited data, we performed a prospective clinical study to investigate the benefit of autologous chondrocyte implantation (ACI) for this demanding patient population.MethodsFifty-one patients displaying at least one of the criteria were included in the present retrospective study: (1.) defect size larger than 10 cm2; (2.) multiple lesions; (3.) kissing lesions, cartilage lesions Outerbridge grade III-IV, and/or (4.) mild/moderate osteoarthritis (OA). For outcome measurements, the International Cartilage Societys International Knee Documentation Committees (IKDC) questionnaire, as well as the Cincinnati, Tegner, Lysholm and Noyes scores were used. Radiographic evaluation for OA was done using the Kellgren score.Results and DiscussionPatients age was 36 years (13-61), defects size 7.25 (3-17.5) cm2, previous surgical procedures 1.94 (0-8), and follow-up 30 (12-63) months. Instruments for outcome measurement indicated significant improvement in activity, working ability, and sports. Mean ICRS grade improved from 3.8 preoperatively to grade 3 postoperatively, Tegner grade 1.4 enhanced to grade 3.39. The Cincinnati score enhanced from 25.65 to 66.33, the Lysholm score from 33.26 to 64.68, the Larson score from 43.59 to 79.31, and Noyes score from 12.5 to 46.67, representing an improvement from Cincinnati grade 3.65 to grade 2.1. Lysholm grade 4 improved to grade 3.33, and Larson grade 3.96 to 2.78 (Table 1), (p < 0.001). Patients with kissing cartilage lesions had similar results as patients with single cartilage lesions.Table 1Mean scores and grades at surgery (Tx) and at follow-upTxFollow-upScoreGradeScoreGradeICRS43Tegner13Noyes1347Cincinnati264662Lysholm334653Larson444793ConclusionOur results suggest that ACI provides mid-term results in patients with complex cartilage lesions of the knee. If long term results will confirm our findings, ACI may be a considered as a valuable tool for the treatment of complex cartilage lesions of the knee.

Calcar comminution as prognostic factor of clinical outcome after locking plate fixation of proximal humeral fractures

OBJECTIVE In the treatment of proximal humeral fractures, the decision between open fixation and arthroplasty is often difficult. Applicable radiographic prognostic factors would be useful. The purpose of the present study was to investigate the influence of calcar comminution on the clinical and radiologic outcome after locking plate fixation of these fractures. METHODS In patients with proximal humeral fractures that were treated by locking plate fixation, fracture morphology and the presence of comminution of the calcar were documented on preoperative radiographs. Follow-up for at least 2 years with radiologic assessment and functional outcome measurements including Constant score, subjective shoulder value (SSV), disabilities of the arm, shoulder and hand score (DASH), visual analogue scale (VAS) and short form (SF)-36 was performed. RESULTS Follow-up examination (50.8±20.6 months) was possible in 74 patients (46 female, 28 male, age 63.0±15.9 years). Mean absolute Constant score (CS abs), CS adapted to age and gender (CS adap), DASH, SSV and VAS were 72.4±14.5, 85.2±17.3%, 15.7±17.3, 80.3±19.6% and 2.1±2.2. Nonunion was present in 1.3%, cut-out in 5.4% and implant failure in 1.3%. Avascular necrosis (AVN) was seen in 12.2%, in three cases >24 months after the initial trauma. In the presence of calcar comminution, the clinical outcome (CS abs, CS adap, SSV and several parameters of SF-36) was significantly impaired, the odds ratio for these patients to have an absolute CS<65 was 4.4 (95% confidence interval (CI): 1.4-13.7). CONCLUSIONS The treatment of proximal humeral fractures with locking plate fixation achieves good clinical mid-term results. Calcar comminution is a relevant and easy-to-detect prognostic factor for the functional and subjective outcome in these fractures.

Posterior screw fixation in rotationally unstable pelvic ring injuries.

OBJECTIVE Although the stability of the pelvic ring primarily depends on the integrity of the posterior sacroiliac arch, lateral compression fractures with rotational instability are commonly treated by anterior fixation alone. The objective of the present study was to assess the outcome of patients with these fractures treated by posterior iliosacral screw fixation alone. METHODS Patients with rotationally unstable lateral compression fractures of the pelvic ring (Young and Burgess LC I and LC II or AO/Tile B2) treated by percutaneous iliosacral fixation alone were included. Postoperative complications, need for secondary surgery, malunion, secondary fracture displacement and the time to full-weight bearing were documented. RESULTS Twenty-five patients (13 female, 26 male; age: 56±20 years) were treated by percutaneous screw fixation (14 bilaterally, 11 unilaterally). Mean follow-up was 6±4 months, mean time to full weight bearing 9±3 weeks. Revision surgery was necessary in two patients (8%) due to nerve irritation; an additional anterior stabilisation was needed in two other patients (8%) due to secondary dislocation. Wound infection or motor weakness were not encountered, non-union of the posterior arch did not occur. Non-union of the pubic rami, however, occurred in two patients. The presence of malunion of the pubic rami did not affect the time to full weight bearing. CONCLUSIONS Percutanous iliosacral screw fixation alone is a sufficient technique for the stabilisation of rotationally unstable pelvic fractures with low rates of complications or non-unions. It allows for a minimally invasive treatment thus being a useful option in patients who do not qualify for open anterior fixation.

Anterior subcutaneous internal fixation for treatment of unstable pelvic fractures

BackgroundFractures of the pelvic ring including disruption of the posterior elements in high-energy trauma have both high morbidity and mortality rates. For some injury pattern part of the initial resuscitation includes either external fixation or plate fixation to close the pelvic ring and decrease blood loss. In certain situations – especially when associated with abdominal trauma and the need to perform laparotomies – both techniques may put the patient at risk of either pintract or deep plate infections. We describe an operative approach to percutaneously close and stabilize the pelvic ring using spinal implants as an internal fixator and report the results in a small series of patients treated with this technique during the resuscitation phase.FindingsFour patients were treated by subcutaneous placement of an internal fixator. Screw fixation was carried out by minimally invasive placement of two supra-acetabular iliac screws. Afterwards, a subcutaneous transfixation rod was inserted and attached to the screws after reduction of the pelvic ring. All patients were allowed to fully weight-bear. No losses of reduction or deep infections occurred. Fracture healing was uneventful in all cases.ConclusionMinimally invasive fixation is an alternative technique to stabilize the pelvic ring. The clinical results illustrate that this technique is able to achieve good results in terms of maintenance of reduction the pelvic ring. Also, abdominal surgeries no longer put the patient at risk of infected pins or plates.

Incidence, Magnitude, and Predictors of Shortening in Young Femoral Neck Fractures.

Objectives: To describe the incidence and magnitude of femoral neck fracture shortening in patients age younger than 60 years. Secondarily, to examine predictors of fracture shortening. Design: Retrospective chart review. Setting: Level I trauma centre. Patients/Participants: Sixty-five patients with a median age of 51 years (interquartile range: 42–56 years) were included. Seventy-one percent were male, 75% were displaced fractures, and 78% were treated with cancellous screws. Intervention: Internal fixation with multiple cancellous screws or sliding hip screw (SHS) + derotation screw. Main Outcome Measurements: Radiographic femoral neck shortening at a minimum of 6 weeks after fixation. Results: Fifty-four percent of patients had ≥5 mm of femoral neck shortening (22% had between ≥5 and <10 mm and 32% ≥10 mm). Initially, displaced fractures shortened more than undisplaced fractures (mean: 8.1 vs. 2.2 mm, P < 0.001), and fractures treated with SHS + derotation screw shortened more than fractures with cancellous screws alone (10.7 vs. 5.5 mm, P = 0.03). Even when adjusting for initial fracture displacement, fractures treated with SHS + derotation screw shortened an average of 2.2 mm more than fractures treated with screws alone (P = 0.03). Conclusions: The incidence of clinically significant shortening in our young femoral neck fracture population was higher than anticipated, and 32% of patients experienced severe shortening of >1 cm. Our findings highlight the need for further research to determine the impact of severe shortening on functional outcome and to determine if implant selection affects fracture shortening. Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Vertebral Body Stenting Versus Kyphoplasty for the Treatment of Osteoporotic Vertebral Compression Fractures A Randomized Trial

BACKGROUND In the treatment of vertebral compression fractures, vertebral body stenting with an expandable scaffold inserted before application of the bone cement was developed to impede secondary loss of vertebral height encountered in patients treated with balloon kyphoplasty. The purpose of this study was to clarify whether there are relevant differences between balloon kyphoplasty and vertebral body stenting with regard to perioperative and postoperative findings. METHODS In a two-armed randomized controlled trial, patients with a total of 100 fresh osteoporotic vertebral compression fractures were treated with either balloon kyphoplasty or vertebral body stenting. The primary outcome was the post-interventional change in the kyphotic angle on radiographs. The secondary outcomes were the maximum pressure of the balloon tamp during inflation, radiation exposure time, perioperative complications, and cement leakage. RESULTS The mean reduction (and standard deviation) of kyphosis (the kyphotic correction angle) was 4.5° ± 3.6° after balloon kyphoplasty and 4.7° ± 4.2° after vertebral body stenting (p = 0.972). The mean pressures were 24 ± 5 bar (348 ± 72 pounds per square inch [psi]) during vertebral body stenting and 16 ± 6 bar (233 ± 81 psi) during balloon kyphoplasty (p = 0.014). There were no significant differences in radiation exposure time.None of the patients underwent revision surgery, and postoperative neurologic sequelae were not observed. Cement leakage occurred at twenty-five of the 100 vertebral levels without significant differences between the two intervention arms (p = 0.230). Intraoperative material-related complications were observed at one of the fifty vertebral levels in the balloon kyphoplasty group and at nine of the fifty levels in the vertebral body stenting group. CONCLUSIONS No beneficial effect of vertebral body stenting over balloon kyphoplasty was found among patients with painful osteoporotic vertebral fractures with regard to kyphotic correction, cement leakage, radiation exposure time, or neurologic sequelae. Vertebral body stenting was associated with significantly higher pressures during balloon inflation and more material-related complications.

Bone mechanical properties and changes with osteoporosis

This review will define the role of collagen and within-bone heterogeneity and elaborate the importance of trabecular and cortical architecture with regard to their effect on the mechanical strength of bone. For each of these factors, the changes seen with osteoporosis and ageing will be described and how they can compromise strength and eventually lead to bone fragility.

Recurrence of acute Charcot neuropathic osteoarthropathy after conservative treatment.

Background: Charcot neuropathic osteoarthropathy (CN) is a chronic, progressive-destructive process affecting the feet of patients with sensory neuropathy. Data on CN recurrence are underrepresented in the literature. The aim of the present study was to evaluate the rate of CN recurrence after its treatment and to find predisposing factors. Methods: Fifty-two patients (age 59 ± 11 years, 16 female) with acute CN with 57 affected feet were enrolled. Comorbidities, localization, and stage of disease at first diagnosis as well as ulcerations, need for surgery, noncompliance, and subsequent treatment (orthopedic footwear or orthotic treatment) during the course of therapy were recorded. During follow-up, the incidence of recurrence of CN was observed. Mean follow-up was 47 ± 40 months. Results: Diabetes was the most common reason for sensory neuropathy (79%). Recurrence of CN was seen in 13 feet (23%) with an interval of 27 ± 31 months (range, 3-102 months) after the end of initial immobilization. Patients with recurrence were immobilized for a shorter period of time and had a more advanced stage of CN at time of first diagnosis. Predictors of recurrence were noncompliance (odds ratio 19.7; confidence interval, 4.1-94.4; P < .001) and obesity (odds ratio 6.4; confidence interval, 1.6-25.9; P = .06). Conclusions: Recurrence of osteoarthropathic activity is a possible complication after conservative treatment of CN. Obesity and noncompliance are strong predictors for the recurrence of CN. Level of Evidence: Level III, retrospective comparative study.