Thomas Tischer

Incidence of Associated Injuries With Acute Acromioclavicular Joint Dislocations Types III Through V

Background Traumatic acromioclavicular (AC) joint dislocations are common injuries among the active population. The injury mechanism requires excessive force delivered by a fall or blow to the shoulder. Associated injuries may occur and remain undetected if they are masked by the painful and prominent AC joint injury. Hypothesis Intra-articular injuries associated with high-grade AC joint dislocations are common. Study Design Case series; Level of evidence, 4. Methods Between 2002 and 2007, 77 patients (68 male, 9 female; average age, 35.5 years; range, 17-62 years) were surgically treated for acute AC joint dislocations (Rockwood type III, 5; type IV, 30; and type V, 42). All patients underwent diagnostic glenohumeral joint arthroscopy. Concomitant intra-articular injuries were identified and treated. Results Intra-articular injuries were found in 14 of 77 patients (18.2%). Superior labral anterior posterior (SLAP) lesions were observed in 11 of 77 patients 14.3% (SLAP I, 3; II, 2; III, 3; and IV, 3). Nineteen percent of Rockwood V lesions had associated SLAP lesions (SLAP I excluded), whereas only 3.4% of Rockwood IV lesions showed SLAP lesions. A complete supraspinatus tear was detected in 1 case, and partial articular-sided supraspinatus tears were detected in 2 cases. Four patients sustained an accompanying fracture. Conclusion Concomitant injuries to the shoulder girdle obtained during traumatic AC joint separation may be more frequent than previously thought. Clinical diagnosis may be difficult in the setting of an acute and painful dislocated AC joint. Shoulder arthroscopy during arthroscopic AC joint stabilization may aid in detecting associated injuries.

Arthroscopic reconstruction of the acromioclavicular joint disruption: surgical technique and preliminary results

Introduction: Numerous operative procedures have been described for the reconstruction of acromioclavicular joint separation; however, the arthroscopic reconstruction has been rarely reported. Therefore, our objective was to propose a new technique of arthroscopic acromioclavicular joint surgery and to evaluate the preliminary results. Materials and methods: Thirteen patients with a mean follow-up of 18 months underwent the arthroscopic acromioclavicular joint reconstruction using suture anchors and small titanium plate. The average age was 40.2 years (range 23–54 years). The shoulders were evaluated using Constant score and radiographs. The indications for surgery included acromioclavicular joint dislocation Rockwood type IV–V. Results: Twelve patients returned to their work without pain within 3 months after operation. The average Constant score at last follow-up was 95. Postoperative radiographs confirmed anatomic reduction in ten patients, residual subluxation in two patients and redislocation of the joint in one patient. One patient had radiographic evidence of coracoclavicular ossification. All patients but one were satisfied with results and cosmetic appearance. Conclusion: Considering its less morbidity, excellent cosmesis, no need of hardware removal, and minimal complications from breakage or migration of metal implants, this new technique offers an attractive alternative in acromioclavicular joint stabilization.

Bisphosphonate-Related Osteonecrosis of the Jaw: Is pH the Missing Part in the Pathogenesis Puzzle?

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a side effect of bisphosphonate therapy, primarily diagnosed in patients with cancer and metastatic bone disease and receiving intravenous administrations of nitrogen-containing bisphosphonates. If diagnosis or treatment is delayed, BRONJ can develop to a severe and devastating disease. Numerous studies have focused on BRONJ, with possible pathomechanisms identified to be oversuppression of bone turnover, ischemia due to antiangiogenetic effects, local infections, or soft tissue toxicity. However, the precise pathogenesis largely remains elusive and questions of paramount importance await to be answered, namely 1) Why is only the jaw bone affected? 2) Why and how do the derivatives differ in their potency to induce a BRONJ? and 3) Why and when is BRONJ manifested? The present perspective reflects on existing theories and introduces the hypothesis that local tissue acidosis in the jaw bone offers a conclusive pathogenesis model and may prove to be the missing link in BRONJ.

Fluorescence-Guided Bone Resection in Bisphosphonate-Related Osteonecrosis of the Jaws: First Clinical Results of a Prospective Pilot Study

PURPOSE Surgical debridement is the therapy of choice in advanced stages of bisphosphonate-related osteonecrosis of the jaws (BRONJ). However, the therapy is currently only loosely standardized because no suitable imaging modalities exist. This study aims to redress this by exploring the suitability and reproducibility of applying a fluorescence-guided bone resection to patients with BRONJ. PATIENTS AND METHODS This prospective pilot study comprised 15 patients with 20 BRONJ lesions (only stages II and III) with a history of intravenous bisphosphonate treatment for metastatic bone diseases. Before surgical treatment, each patient received a 10-day administration of doxycycline. Fluorescence-guided resection of necrotic bone was performed by means of a certified fluorescence lamp. Success of the procedure was proclaimed if mucosal closure was observed and symptoms were absent 4 weeks postoperatively. RESULTS The 4-week postoperative follow-up identified a mucosal closure in 17 of 20 BRONJ lesions (85%). These patients were free of any symptoms. Failure as defined by mucosal dehiscence and exposed bone was observed in 3 of 20 BRONJ lesions (15%). CONCLUSION The success rate of this surgical regimen of BRONJ was respectable, and thus fluorescence-guided bone resection can be considered an effective treatment for stage II and stage III BRONJ. Furthermore, the reproducibility of the technique offers an opportunity to standardize the surgical therapy. Further studies are called for that compare the fluorescence-guided bone resection with conventional surgical approaches, as well as surgical versus conservative treatment in the early stages (stages 0 and I) of BRONJ.

Fluorescence-Guided Bone Resection in Bisphosphonate-Associated Osteonecrosis of the Jaws

PURPOSE To date, the therapy of bisphosphonate-associated osteonecrosis of the jaws (BONJ) has been hampered by the lack of imaging modalities that enable the extent of necrosis to be visualized. This study aims to demonstrate the feasibility of tetracycline fluorescence guided bone resection in the surgical management of BONJ. PATIENTS AND METHODS Following a 10-day preoperative administration of doxycycline in patients suffering from BONJ, sufficient doxycycline is incorporated into viable bone to be visualized with a certified medical lamp emitting exciting light at 400 to 460 nm. RESULTS Viable and necrotic bone can be discriminated intraoperatively in a routine and reproducible manner by doxycycline bone fluorescence. CONCLUSION In the therapy of BONJ, conservative concepts are to be favored. The fact that necrotic bone can now be selectively resected signifies an improvement of the conservative surgical therapy of BONJ.

Arthroscopic Repair of Anterior-Inferior Glenohumeral Instability Using a Portal at the 5:30-o’Clock Position Analysis of the Effects of Age, Fixation Method, and Concomitant Shoulder Injury on Surgical Outcomes

Background: Traumatic anterior-inferior shoulder joint dislocations are common injuries among the young athletic population. The aim of this study was to assess which factors, including concomitant injury (rotator cuff tears, superior labral anterior posterior [SLAP] lesions), patient age, and fixation methods, led to redislocation after arthroscopic stabilization. Hypothesis: There are several risk factors for the outcome after arthroscopic anterior-inferior glenohumeral stabilization. Study Design: Cohort Study; Level of evidence, 3. Methods: Between 1996 and 2000, 221 patients were treated with arthroscopic stabilization for anterior-inferior shoulder dislocation. Of these 221 consecutive patients, 190 (140 male, 50 female) with an average age of 28.0 years (range, 14.4-59.2 years) were available for follow-up (average follow-up, 37.4 ± 15.8 months). Fixation methods were FASTak (n = 138), Suretac (n = 28), or Panalok (n = 24) anchors. Concomitant SLAP lesions were seen in 38 of 190 cases (20%). Results: Redislocation rates varied between anchor systems (FASTak, 6.5%; Suretac, 25%; Panalok, 16.8%). Superior labral anterior posterior lesions, when treated, did not influence clinical outcomes or redislocation rate. A concomitant rotator cuff tear did not influence redislocation rate. Postoperative outcomes (Rowe score, Constant score, American Shoulder and Elbow Surgeons [ASES] shoulder index, 12-item questionnaire) in patients with a partial tear were also not altered. On the other hand, the redislocation rate correlated with patient age and number of prior dislocations. Return to sports at preinjury level was possible in 80% of cases. Conclusion: Arthroscopic repair of anterior-inferior instability using the 5:30-o’clock portal is dependent on anchor type and can show good to excellent results. Because of several coinjuries in anterior-inferior instability, an arthroscopic approach may be required to identify and treat such lesions.

Bisphosphonate related osteonecrosis of the jaw: A minipig large animal model☆

Bisphosphonate related osteonecrosis of the jaw (BRONJ) is rare but potentially severe, and the etiopathology and risk factors are poorly defined. To date, it has not been possible to induce BRONJ in a large animal model, a shortfall this study aims to redress. Ten two-year-old adult Göttingen minipigs were split into two groups. Five pigs (group 1) were administered intravenously a weekly dose of a bisphosphonate (zoledonate 0.05mg/kg body weight, approximating the oncologic dose in humans) and five pigs (group 2) served as controls. After 6 weeks, tooth extractions were performed in the upper and lower jaw (both groups) and the bisphosphonate administration continued for a further 10 weeks (group 1 only). Clinical and blood parameters were monitored throughout the entire experiment; thereafter, the jaw-bones were subjected to macroscopic, radiological (CT) and histological investigations. Whilst the extraction sites in the control group healed within two weeks, all animals in the bisphosphonate group exhibited exposed bone and impaired wound healing, indicators that are synonymous of macroscopically advanced osteonecrosis. Radiological and in particular histological investigations confirmed the presence of BRONJ in the animals from group 1. This paper demonstrates that the administration of bisphosphonates, in combination with tooth extractions, induces BRONJ in a minipig model. The ability to study BRONJ in miniature pigs, animals with a bone structure not dissimilar to humans, may improve our knowledgebase regarding the etiopathology, the prophylaxis and potentially uncover new therapies of BRONJ.

Tetracycline Bone Fluorescence: A Valuable Marker for Osteonecrosis Characterization and Therapy

PURPOSE Differential diagnosis of osteoradionecrosis and bisphosphonate-related osteonecrosis of the jaw is primarily based on medical history, rather than pathogenesis or histopathology. This report aims to redress this shortcoming by demonstrating the advantages of tetracycline bone fluorescence as an aid to characterize osteonecrosis entities according to differential histopathologies. Furthermore, this technique facilitates the means to determine extent of necrosis and to optimize surgical therapy. PATIENTS AND METHODS Two patients with extended osteonecrosis of the lower jaw (osteoradionecrosis or bisphosphonate-related osteonecrosis of the jaw) were treated with partial mandibulectomy. After preoperative administration of doxycycline for 10 days, bone fluorescence was monitored intraoperatively to determine the resection boundaries. RESULTS Fluorescence analysis correlated well with the specific histopathologic features of the 2 osteonecrosis entities. Bone fluorescence was predominantly observed in the cortical bone and cancellous bone regions in osteoradionecrosis and bisphosphonate-related osteonecrosis of the jaw, respectively. Margins of the osteonecrosis (and the resection) could be determined under fluorescence guidance; however, bone bleeding did not correlate with bone fluorescence in both osteonecrosis entities. CONCLUSIONS Given that viable but not necrotic bone displays tetracycline fluorescence, a notion that reflects the histopathology, more precise characterization of the 2 osteonecrosis types is enabled. Furthermore, even in extended cases of osteonecrosis requiring partial mandibulectomy, bone fluorescence helps to pinpoint the margins of resection and thus signifies an improvement of surgical therapy of extended osteonecrosis.

Generation and characterization of a human acellular meniscus scaffold for tissue engineering

Meniscus tears are frequent indications for arthroscopic evaluation which can result in partial or total meniscectomy. Allografts or synthetic meniscus scaffolds have been used with varying success to prevent early degenerative joint disease in these cases. Problems related to reduced initial and long-term stability, as well as immunological reactions prevent widespread clinical use so far. Therefore, the aim of this study was to develop a new construct for tissue engineering of the human meniscus based on an acellular meniscus allograft. Human menisci (n = 16) were collected and acellularized using the detergent sodium dodecyl sulfate as the main ingredient or left untreated as control group. These acellularized menisci were characterized biomechanically using a repetitive ball indentation test (Stiffness N/mm, residual force N, relative compression force N) and by histological (hematoxylin-eosin, phase-contrast) as well as immunohistochemical (collagen I, II, VI) investigation. The processed menisci histologically appeared cell-free and had biomechanical properties similar to the intact meniscus samples (p > 0.05). The collagen fiber arrangement was not altered, according to phase-contrast microscopy and immunohistochemical labeling. The removal of the immunogenic cell components combined with the preservation of the mechanically relevant parts of the extracellular matrix could make these scaffolds ideal implants for future tissue engineering of the meniscus.

A Fibrin Glue Composition as Carrier for Nucleic Acid Vectors

PurposeGene delivery from biomaterials has become an important tool in tissue engineering. The purpose of this study was to generate a gene vector-doted fibrin glue as a versatile injectable implant to be used in gene therapy supported tissue regeneration.MethodsCopolymer-protected polyethylenimine(PEI)-DNA vectors (COPROGs), naked DNA and PEI-DNA were formulated with the fibrinogen component of the fibrin glue TISSUCOL® and lyophilized. Clotting parameters upon rehydration and thrombin addition were measured, vector release from fibrin clots was determined. Structural characterizations were carried out by electron microscopy. Reporter and growth factor gene delivery to primary keratinocytes and chondrocytes in vitro was examined. Finally,chondrocyte colonized clots were tested for their potency in cartilage regeneration in a osteochondral defect model.ResultsThe optimized glue is based on the fibrinogen component of TISSUCOL®, a fibrin glue widely used in the clinics, co-lyophilized with copolymer-protected polyethylenimine(PEI)- DNA vectors (COPROGs). This material, when rehydrated, forms vector-containing clots in situ upon thrombin addition and is suitable to mediate growth factor gene delivery to primary keratinocytes and primary chondrocytes admixed before clotting. Unprotected PEI-DNA in the same setup was comparatively unsuitable for clot formation while naked DNA was ineffective in transfection. Naked DNA was released rapidly from fibrin clots (>70% within the first seven days) in contrast to COPROGs which remained tightly immobilized over extended periods of time (0.29% release per day). Electron microscopy of chondrocytecolonized COPROG-clots revealed avid endocytotic vector uptake. In situ BMP-2 gene transfection and subsequent expression in chondrocytes grown in COPROG clots resulted in the upregulation of alkaline phosphatase expression and increased extracellular matrix formation in vitro. COPROG-fibrinogen preparations with admixed autologous chondrocytes when clotted in situ in osteochondral defects in the patellar grooves of rabbit femura gave rise to luciferase reporter gene expression detectable for two weeks (n=3 animals per group). However, no significant improvement in cartilage formation in osteochondral defects filled with autologous chondrocytes in BMP-2-COPROG clots was achieved in comparison to controls (n=8 animals per group).ConclusionsCOPROGs co-lyophilized with fibrinogen are a simple basis for an injectable fibrin gluebased gene-activated matrix. The preparation can be used is complete analogy to fibrin glue preparations that are used in the clinics. However, further improvements in transgene expression levels and persistence are required to yield cartilage regeneration in the osteochondral defect model chosen in this study.