Survivorship, complications and patient-reported outcomes in calcar-guided short-stem THA: prospective mid-term multicenter data of the first 879 hips.

INTRODUCTION: Short stems are a bone and soft-tissue preserving alternative to conventional stems. The aim of this multicenter study is to present the mid-term outcomes of a calcar-guided short stem. MATERIALS AND METHODS: This is a prospective case series of the first 879 total hip arthroplasties performed on 782 patients across 5 centers using identical calcar-guided short stems. In a mid-term follow-up (6 years), rates and reasons for complications and revisions were documented. The Harris Hip Score (HHS) was obtained; patients reported pain and satisfaction using a visual analog scale. RESULTS: A total of 43 patients died in the study cohort for non-related reasons; 26 patients (3.0%) required at least 1 revision after the index procedure. The survival rate for endpoint stem revision at mid-term was 98.4%. The main reasons for stem revision were aseptic loosening and early periprosthetic fractures. Sex had no influence on stem survival. Older patients or those with a high body mass index showed increased risk for stem revision during follow-up. Dorr type A morphology revealed a significantly lower risk of stem revision than Dorr type B or C (p = 0.0465). The HHS, satisfaction, and load pain at mid-term were 96.5 (SD 8.0), 9.7 (SD 0.9), and 0.5 (SD 1.9), respectively. CONCLUSIONS: This short stem produced highly satisfactory outcomes at mid-term, with 98.4% implant survival for any cause of stem revision and low complication rates. Long-term results are required to further evaluate these promising mid-term results.

[Giant cell reparative granuloma of the metacarpal bone : Diagnostic difficulties]. / Das reparative Riesenzellgranulom des Os metacarpale : Differenzialdiagnostische Schwierigkeiten.

Giant cell reparative granuloma (GCRG) is benign, non-tumorous granulation tissue. It mainly arises in the jaw bone and occasionally in the hand and foot. Because of the high rate of recurrence, wide surgical resection and autologous bone grafting are recommended. However, this can be problematic for hand function. We present a case report of a 16-year-old boy with a GCRG of the fifth metacarpal bone and the diagnostic difficulties. To treat the patient, we performed a wide resection with the interposition of a corticocancellous bone graft and plate osteosynthesis. 24 months postoperatively the patient shows no signs of recurrence and has good hand function.

Current therapeutic strategies of heterotopic ossification--a survey amongst orthopaedic and trauma departments in Germany.

BACKGROUND: Heterotopic ossification (HO) is a complication after tissue trauma, fracture and surgery (i.e. total hip arthroplasty). Prophylaxis is the most effective therapy. If HO formations become symptomatic and limit patients' quality of life, revision surgery is indicated and is usually combined with a perioperative oral prophylaxis (NSAIDs) and/or irradiation. However, a long-term use of NSAIDs can induce gastro-intestinal or cardiac side-effects and possible bony non-unions during fracture healing. Subject of this study was to assess the current status of HO prophylaxis after injuries or fractures and to evaluate current indications and strategies for excision of symptomatic HO. METHODS: Between 2013 and 2014, a questionnaire was sent to 119 orthopaedic and trauma surgery departments in Germany. Participation was voluntary and all acquired data was given anonymously. RESULTS: The cumulative feedback rate was 71 %. Trauma and orthopaedic surgery departments in Germany recommend oral HO prophylaxis after acetabulum and femoral neck fractures, elbow dislocation, and fracture or dislocation of the radial head. Pain upon movement and an increasing loss of range of motion in the affected joint are considered to be clear indications for HO surgery. A partial removal of ROM-limiting HO formations was also considered important. The vast majority of all departments include perioperative oral HO prophylaxis and/or irradiation if surgical HO removal is planned. The choice and duration of NSAIDs is highly variable. CONCLUSION: HO is of clinical significance in current traumatology and orthopaedics. Certain fractures and injuries are prone to HO, and prophylactic measures should be taken. The respondents in this survey assessed current therapeutic strategies for HO formations similarly. These concepts are in line with the literature. However, the duration of perioperative oral HO prophylaxis varied greatly among the specialist centres. This is significant as a long-term use of NSAIDs fosters a potential risk for the patients' safety and could influence the clinical outcome. National and international guidelines need to be developed to further reduce HO rates and improve patients' safety in trauma and orthopaedic surgery.

The impact of hypoxia on mesenchymal progenitor cells of human skeletal tissue in the pathogenesis of heterotopic ossification.

PURPOSE: Mesenchymal progenitor cells (MPCs) are capable of differentiating into osteo/chondrogenic cells to contribute substantially to heterotopic ossification (HO). This study aimed to examine the impact of hypoxia on MPCs in the aetiology of HO. METHODS: MPCs from human normal and HO skeletal tissue were cultivated under normoxia and hypoxia. Gene expression of factors which have a key role in HO aetiology (BMPs, COX-1 and COX-2, etc.) were examined by real-time PCR. Tissue of both groups was analysed by immunohistochemistry. RESULTS: Under hypoxia, COX-1, -2 and SOX-9 gene expression was elevated in HO MPCs, whereas in normal muscle tissue only COX-2 was upregulated. MPCs from HO had a significantly elevated gene expression of BMP-4 and decreased expression of BMP-1 and HIF-1 under hypoxia compared to normal MPCs. Immunohistochemistry detected no significant differences between normal and HO tissue. CONCLUSIONS: Hypoxia causes an enhanced gene expression of factors, which have a key role in HO pathophysiology. A better understanding of this entity will possibly allow reducing HO rates in orthopaedic and trauma surgery.

Bisphosphonates or prostacyclin in the treatment of bone-marrow oedema syndrome of the knee and foot.

Bone-marrow oedema (BME) represents a reversible but mostly painful increase in interstitial fluid. The exact pathogenetic processes still remain unknown. Treatment options are mainly symptomatic with core decompression as golden standard leading to immediate pain relieve. Recently, it has been shown that intravenous prostacyclin and bisphosphonates are useful in achieving a reduction in BME with a considerable improvement in the accompanying symptoms. We compared the outcome of both intravenously applied prostacyclin (Ilomedin(®), 10 patients) and bisphosphonate (Bondronat(®), 10 patients) in treatment of BME of the knee and foot. We could find a significant improvement of WOMAC score, SF-36 score and VAS 3 months and 1 year after therapeutic intervention in both the prostacyclin and the bisphosphonate group. Concerning the MRI scans in both groups, we found a distinct reduction of BME in 47 % and a complete regression in 40 %. Comparing both groups, the improvement of the scores was greater in the prostacyclin group than in the bisphosphonate group; the difference, however, was not significant. Intravenous bisphosphonates as well as prostacyclin are of efficient therapeutic benefit in treatment of BME with a quicker and greater effect of prostacyclin.

Gait analysis after tibialis anterior tendon rupture repair using Z-plasty.

Other than limited reports regarding surgical outcomes, little information is available regarding whether Z-plasty of the tibialis anterior results in normal gait kinematics. We included 5 patients with spontaneous ruptures in the present retrospective study. The mean interval between rupture and operative treatment was 2.6 ± 2.6 months (standard deviation). The mean age of the patients was 63 (range 40 to 80) years. All patients were treated operatively with Z-plasty. Gait analysis was used to study the outcome, comparing the operated and nonoperated limbs. The patients were tested after a mean follow-up of 22 (range 12 to 33) months. No repeat ruptures were noted. Plantarflexion was significantly diminished during the preswing phase and initial swing phase in the operated limbs compared with the uninjured limbs. Plantarflexion was significantly increased during the terminal swing phase on the operated side. Knee flexion was nearly symmetrical. No significant differences regarding the temporospatial parameters were noted. We recommend Z-plasty for ruptures of the tibialis anterior tendon as a safe and effective procedure. However, this technique does not fully restore a physiologic gait pattern.

Correlation of ultrasonographic findings to Tossy's and Rockwood's classification of acromioclavicular joint injuries.

The aim of this study was to examine the value of ultrasonography to assess high-graded acromioclavicular (AC) joint injuries. We propose a new sonographic technique to evaluate the state of the soft tissues, specifically the deltoid and trapezoid muscles and their common fascia. Radiologic findings graded by Tossy's and Rockwood's classification were compared with sonographic findings for 92 patients with high-grade injuries of the AC joint. Of the 92 patients, 39 underwent operative treatment. A total of 36 patients were radiographically classified as type II and 56 with type III injuries, according to Tossy. In 4 cases, ultrasonography displayed disrupted insertions of the deltoid and, in 30 patients, of the trapezius muscle. All patients classified as type V, eight of 18 patients classified as type IV, nine of 31 patients classified as type III and two of 28 patients classified as type II injuries, according to Rockwood's classification, displayed a disrupted deltoid and trapezius insertion and common fascia on ultrasound (US). Comparison between sonographic and intraoperative findings revealed a sensitivity for diagnosing delta muscle detachment and fascial disruption of 100%. No true-negative results occurred. For trapezius muscle detachment, 24 of 30 patients were diagnosed correctly and nine true-negative results occurred. False-positive results were not encountered. The sensitivity was 80%. The specificity was 100%. We conclude that US provides additional information concerning soft tissues and that it may be useful to delineate type III injuries, in which nonoperative vs. operative treatment is still being debated. Diagnosis based only on sagittal X-ray examination may under- or over-estimate the soft tissue injury involved. Additional transaxillary X-ray as well as an US evaluation may need to be included in the diagnostic process. We propose this new sonographic technique for future studies.

Ultrasound-guided decompression of the spinal canal in traumatic stenosis.

The purpose of this study was to examine the efficacy of ultrasound (US)-guided decompression of the myelon in the surgical treatment of spinal fractures. Intraoperative ultrasonography was performed in 22 patients with traumatic stenosis of the spinal canal during spinal cord surgery with removal of retropulsed bony fragments. US imaging requires a posterior approach and an enlarged foramen interarcuale. The posterior vertebral facet and the myelon can accurately be distinguished from small bony fragments by ultrasonography. Pre- and postoperative computed tomography was compared with intraoperative US imaging. Complete decompression of the spinal canal was controlled by US imaging of the restored ventral epidural space, as seen after repositioning of displaced fragments. Thus, the required extent of the surgical procedure was determined by intraoperative ultrasonography. We conclude that intraoperative US imaging is an important tool to monitor the restoration of the spinal canal and decompression of the spinal cord in case of fracture. The repositioning of stenosing bony fragments using surgical instruments can be monitored. US imaging as a real-time method intraoperatively provides the surgeon with additional information and significantly influences treatment options.

Measurement of muscle activity with magnetic resonance elastography.

OBJECTIVE: To non-invasively determine muscle activity. DESIGN: A correlation analysis study. BACKGROUND: Electromyography is traditionally used to measure the electrical activity of a muscle and can be used to estimate muscle contraction intensity. This approach, however, is limited not only in terms of the volume of tissue that can be monitored, but must be invasive if deep lying muscles are studied. We wished to avoid these limitations and used magnetic resonance elastography in an attempt to non-invasively determine muscle activity. This novel approach uses a conventional MRI system. However, in addition to the imaging gradients, an oscillating, motion sensitizing field gradient is applied to detect mechanical waves that have been generated within the tissue. The wavelength correlates with the stiffness of the muscle and hence with the activity of the muscle. METHODS: Six volunteers (mean age: 30.1 years, range: 27-36 years) without orthopedic or neuromuscular abnormalities, lay supine with their legs within the coil of a MRI scanner. The wavelengths of mechanically generated shear waves in the tibialis anterior, medial and lateral head of the gastrocnemius and the soleus were measured as the subjects resisted ankle plantar-flexing (8.2 and 16.4 nm) and dorsi-flexing (20.2 and 40.4 nm) moments. The findings were then compared to EMG data collected under the same loading conditions. RESULTS: Magnetic resonance elastography wavelengths were linearly correlated to the muscular activity as defined by electromyography. (TA, R(2)=0.89, P=0.02; MG, R(2)=0.82, P=0.05; LG, R(2)=0.88, P=0.03; S, R(2)=0.90, P=0.02) CONCLUSIONS: Magnetic resonance elastography may be a promising tool for the non-invasive determination of muscle activity. RELEVANCE: Magnetic resonance elastography has potential as the basis for a new non-invasive approach to study in vivo muscle function.

Development and evaluation of an image-free computer-assisted impingement detection technique for total hip arthroplasty.

Periprosthetic or bony impingement in total hip arthroplasty (THA) has been correlated to dislocation, increased wear, reduced postoperative functionality with pain and/or decreased range of motion (ROM). We sought to study the accuracy and assess the reliability of measuring bony and periprosthetic impingement on a virtual bone model prior to the implantation of the acetabular cup with the help of image-free navigation technology in an experimental cadaver study. Impingement-free ROM measurements were recorded during minimally invasive, computer-assisted THA on 14 hips of 7 cadaveric donors. Preoperatively and postoperatively the donors were scanned using computed tomography (CT). Impingement-free ROM on three-dimensional CT-based models was then compared with corresponding, intraoperative navigation models. Bony/periprosthetic impingement can be detected with a mean accuracy limit of below 5° for motion angles, which should be reached after THA for activities of daily living with the help of image-free navigation technology.

MR imaging of the intraarticular disk of the acromioclavicular joint: a comparison with anatomical, histological and in-vivo findings.

OBJECTIVE: To characterize MRI features of the intraarticular disk of the acromioclavicular joint. DESIGN: We studied the appearance of 11 acromioclavicular joints of six cadavers (subjects aged 57-89 years at the time of death) and six healthy shoulders on T1-weighted, T2 (TSE)-weighted, STIR and PD (fat saturated) magnetic resonance imaging (MRI) and compared the findings with observations during dissection and histological examination. RESULTS: Macroscopic examinations showed two wedge-shaped disks underneath the superior and above the inferior joint capsule in nine specimens. In two specimens the acromioclavicular joints were degenerated. Histologically, the disk tissue consisted of fibrocartilage whereas the joint cartilage was partly degenerated, containing zones of fibrocartilage amidst degenerated hyaline cartilage, which may explain the similar signal intensity of both structures in all sequences used. MR appearance of the intraarticular structures of the acromioclavicular joint was similar in cadaveric and healthy shoulders. CONCLUSIONS: The difficulties related to imaging the acromioclavicular joint may be explained by the anatomy. Similar signal intensity of cartilage and disk may be explained by their similar histological structure (fibrocartilage). MRI findings should be interpreted with respect to the variable anatomy. These results may serve as a basis for further radiological studies of the acromioclavicular joint.

Biomechanical effect of patch graft for large rotator cuff tears: a cadaver study.

It is not possible for some rotator cuff tears to be repaired because of a large defect associated with muscle retraction. The purpose of the current study was to investigate the use of a synthetic patch graft to restore abduction force transmission in the glenohumeral joint with a rotator cuff defect. Shoulders from cadavers (n = 10) were fixed in the hanging arm and in neutral rotation, and loading was applied to the rotator cuff tendons and middle deltoid. After a simulated supraspinatus tendon defect and retraction, a patch graft was inserted into the defect and the effects of reattachment to the greater tuberosity, narrowing of the defect by using a smaller graft, and anterior graft attachment (rotator interval tissue versus subscapularis) were investigated. Abduction torque generation was measured and normalized to the intact condition. Compared with torque generation after creation of a supraspinatus defect (61% of normal torque), abduction torque increased with a graft between the infraspinatus and either the rotator interval (68% of normal) or subscapularis (80% of normal). The optimum grafting technique for abduction torque restoration occurred with a reduced size patch connected anteriorly to the subscapularis and sutured to the greater tuberosity (107% of normal). The patch graft acts to redirect force transmission, thereby providing a potential treatment option for otherwise irreparable defects. These same principles can be applied when tendon transfers are used to reconstruct large or massive cuff tears.

Evaluation of healthy and diseased muscle with magnetic resonance elastography.

OBJECTIVE: To investigate whether a new tissue-imaging technique, magnetic resonance elastography (MRE), offers a viable, noninvasive way to study healthy and diseased muscle. DESIGN: Convenience sample. SETTING: A magnetic resonance imaging (MRI) laboratory. PARTICIPANTS: Eight control subjects (4 men, 4 women), between the ages of 24 and 41 years, with normal neuromuscular examinations and histories, and 6 subjects (3 men, 3 women), ages 17 to 63 years, with lower-extremity neuromuscular dysfunction (1 with childhood poliomyelitis, 2 with flaccid, 3 with spastic paraplegia). INTERVENTIONS: Subjects lay supine with their legs within the coils of a 1.5T MRI machine, with their feet strapped to a footplate positioned so that the axes of rotation of their ankles coincided with the apparatus. All subjects were tested in a no-load (0 torque) condition. Control subjects were also evaluated as they isometrically resisted ankle dorsi- (20.2Nm, 40.5Nm) and plantar- (8.2Nm, 16.4Nm) flexion moments. Subjects with neuromuscular dysfunction were evaluated in the same manner, except 1 individual with residual lower-extremity strength who could only be tested in the resting and passive ankle dorsiflexion modes. Shear waves were induced with a 150-Hz electromechanic transducer located over the belly tibialis anterior. MRE images were collected with a gradient-echo technique gated to the transducer's motion. Wave-phase propagation was visualized with 8 equally offset images across 1 vibration-cycle. MAIN OUTCOME MEASURES: Changes in shear-wave wavelength (lambda) and muscle stiffness (as expressed by the shear modulus [G]) in the tibialis anterior and gastrocnemius muscles. RESULTS: Wavelength and G differed between the groups in all the muscles studied, and increased as the load increased. Moreover, lambda and G in the neuromuscular disease group at rest (eg, 3.88+/-0.48cm; range, 2.87-4.91cm; 38.40+/-00.77kPa; range, 22.35-59.67kPa) and in the lateral gastrocnemius were, respectively, more than 1.5 and 2.4 times larger than they were in the same muscle in the control group (2.56+/-0.28cm, 16.16+/-00.19kPa; P=.0002) (1Pa=1N/m(2)). CONCLUSIONS: Shear-wave wavelength and muscle stiffness increased with load in healthy muscle. In addition, at least for our sample, these quantities differed significantly between muscles with and without neuromuscular disease. In summary, MRE appears to provide in vivo physiologic information about the mechanical properties of muscle at rest and during contraction that is not otherwise available. The potential of this technique for monitoring the effects of treatment and exercise on both healthy and diseased muscle merits further research.

The effect of infraspinatus disruption on glenohumeral torque and superior migration of the humeral head: a biomechanical study.

Rotator cuff ruptures that extend into the infraspinatus tendon may cause dysfunction and superior migration of the humerus. The purpose of this study was to determine whether a threshold size of infraspinatus defect exists beyond which abduction torque generation decreases and superior migration of the humeral head increases. Glenohumeral abduction torque and superior humeral head translations were measured in hanging arms in neutral rotation in cadaver shoulders (n = 10). Loads were applied to the rotator cuff tendons and the middle deltoid. After sequential detachment of the infraspinatus, abduction torque progressively decreased. At three-fifths detachment, abduction torque was significantly lower than after supraspinatus release alone (52% vs 61%, P <.05). Superior translation after complete supraspinatus and infraspinatus detachment increased significantly (P <.05), but no intermediate threshold was detected. Therefore, the entire infraspinatus contributes to abduction torque generation and stabilizes the humeral head against superior subluxation. Even with a tear extending into the superior infraspinatus, the infraspinatus contributes abduction force generation across the glenohumeral joint.