Bone Replacement Materials in Hand Surgery

Abstract Background: In recent years, biomaterials are being found and frequently utilized in bone defects. They have also gained significant precedence in hand surgery. Objectives: The respective requirements for such replacement material will be cited and acknowledged in this article. The individual material groups will also be referred to in this review. An introduction to some of the customary bone replacement materials will be cited and concluded with a corresponding recommendation. Conclusion: The implantation of autologous cancellous bone is still regarded today as the “gold standard”. Nevertheless, the usage of bone replacement material can be an enormous advantage in certain indications. The original article can be found online at There was an error in the author’s affiliation and the address for correspondence was incomplete. Please note the correct institution and complete address: Department of Orthopedics and Traumatology, Hand-, Foot- and Reconstructive Surgery, Kreiskrankenhaus Gummersbach GmbH, Germany. Alexander von Friesen, MD Department of Orthopedics and Traumatology, Hand-, Foot- and Reconstructive Surgery Kreiskrankenhaus Gummersbach GmbH Wilhelm-Breckow-Allee 20 51643 Gummersbach Germany Phone (+49/2261) 171-575, Fax -449 e-mail: Friesen@kkh-gummersbach.de     

Downward deviation of progressive addition lenses in a myopia control trial

PURPOSE: To clarify how the downward deviation of progressive addition lenses (PALs) reduces their near-addition effect in schoolchildren participating in a myopia control trial. METHODS: Among 95 schoolchildren wearing PALs for 6 months (age range: 6-12 years; refractive error range: -6.00 to -1.25 D), facial images were captured with a digital still camera placed 60 cm in front of the eyes while he or she was looking ahead with natural head posture. The vertical deviations of PALs from their ideal position (mm) were evaluated by analysing these images. RESULTS: The mean (+/-SD) downward deviations of PALs for the right and left eyes were 3.7 +/- 2.3 and 3.7 +/- 2.0 mm, respectively, and the largest downward deviation was 10.2 mm. For simulations using the average downward deviation, the near-addition effect of PALs was reduced to 30 and 63% of the expected value at the 10 degrees and 20 degrees downward eye positions, respectively. CONCLUSIONS: The downward deviation of PALs is a significant factor in reducing their therapeutic effect for near-addition. To ensure the proper alignment of PALs in children, the conventional spectacle-frame-fitting procedure is not sufficient, and repeated confirmation using a testing method similar to that used in this study is required.     

Extrinsic risk factors for compromised blood flow in the vertebral artery: anatomical observations of the transverse foramina from C3 to C7

The vertebral artery (VA) is often involved in the occurrence of complications after spinal manipulative therapy. Due to osteophytes compressing the VA anteriorly from the uncinate process or posteriorly from the facet complex, the VAs are susceptible to trauma in the transverse foramina. Such altered anatomical configurations are of major clinical significance, as spinal manipulations may result in dissection of the VA with serious consequences for the blood supply to the vertebrobasilar region. The purpose of this study is to describe numerous structural features of the third to seventh cervical vertebrae in order to contribute to the understanding of pathological conditions related to the VA. The minimal and maximal diameter of 111 transverse foramina in dry cervical vertebrae were studied. The presence of osteophytes and their influence on the VA were evaluated at the vertebral body and at the superior and inferior articular facets. The diameter of the transverse foramina increased from C3 to C6, while the transverse foramina of C7 had the smallest diameter. At all levels the mean dimensions of the left foramina were greater than those of the right side. Osteophytes from the uncinate process of C5 and C6 vertebrae were found in over 60% of dry vertebrae. Osteophytes from the zygapophyseal joints were more frequent at C3 and C4 vertebrae. About half of the osteophytes of the uncinate and of the superior articular process partially covered the transverse foramina. This was less common with those of the inferior articular facets. Osteophytes covering the transverse foramen force the VAs to meander around these obstructions, causing narrowing through external compression and are potential sites of trauma to the VAs potentially even leading to dissection. We strongly advocate that screening protocols for vertebrobasilar insufficiency (VBI) be used prior to any manipulation of the cervical spine and should include not only extension and rotation but any starting position from which the planned manipulation will be performed.     

Magnetic and electrical stimulation of undulating nerve fibres: a simulation study

Mathematical models of myelinated nerve fibres are highly stylized abstractions of real nerve fibres. For example, nerve fibres are usually assumed to be perfectly straight. Such idealizations can cause discrepancies between theoretical predictions and experimental results. One well-known discrepancy is that the currently used models predict (contradictory to experimental findings) that an activation of nerve fibres is not possible with a pure transverse electric field. This situation occurs when a magnetic coil is placed symmetrically above a straight nerve fibre for magnetic nerve stimulation, or when an anode and a cathode are placed equidistantly on a line perpendicular to the fibre in the case of electrical stimulation. It is shown that this discrepancy does not occur if the physiological undulation of peripheral nerve fibres is included in the models. Even for small undulation amplitudes (e.g. 0.02 mm), it is possible to activate the fibre in these positions. For physiological undulations, as found in the literature, and favourable (off-centre) positions, the typical reduction of the thresholds is in a range between one and five, compared with perfectly straight fibres.     

动力加压髁螺钉治疗股骨髁部骨折临床与实验研究

本研究结合１４例股骨髁间、髁上骨折以动力加压髁螺钉（Ｄynamic Ｃondylar Ｓcrew ＤＣＳ）固定。目的：为临床提供应用ＤＣＳ的实验数据。方法：采用成人新鲜尸体股骨髁部标本,按照ＡＯ/ＡＳＩＦ分类,模拟Ｙ形骨折模型,以ＤＣＳ固定,置于ＷＤ－１０Ｅ万能电子力学实验机上其抗拉伸、抗扭转、抗村缩、抗剪切强度。结果：ＤＣＳ有较好的固定强度。临床应用１４例,随访６个月至１年,优良率为８５．７１％。结论：ＤＣＳ适合于     

A new approach to the study of ocular chromatic aberrations

We measured the ocular wavefront aberration at six different visible wavelengths (between 450 and 650 nm) in three subjects, using a spatially resolved refractometer. In this technique, the angular deviation of light rays entering the pupil at different locations is measured with respect to a target viewed through a centered pupil. Fits of the data at each wavelength to Zernike polynomials were used to estimate the change of defocus with wavelength (longitudinal chromatic aberration, LCA) and the wavelength-dependence of the ocular aberrations. Measured LCA was in good agreement with the literature. In most cases the wavefront aberration increased slightly with wavelength. The angular deviations from the reference stimulus measured using a magenta filter allowed us to estimate the achromatic axis and both optical and perceived transverse chromatic aberration (TCA), (including the effect of aberrations and Stiles-Crawford effect). The amount of TCA varied markedly across subjects, and between eyes of the same subject. Finally, we used the results from these experiments to compute the image quality of the eye in polychromatic light.     

A dermoid cyst fistulating with the transverse colon

We present a rare case of fistulation of a dermoid cyst with the transverse colon. We illustrate how an infected dermoid cyst can be diagnosed as an appendix abscess although the management of these is quite different. The general surgeon should be aware of this as a differential diagnosis for an appendix abscess.     

峡部植骨修复拉力螺钉张力带固定治疗青少年下腰椎峡部裂

目的　探讨青少年下腰椎峡部裂的治疗中直接峡部植骨修复拉力螺钉张力带固定手术方法及其价值。　方法　共 12例 ,年龄范围 12 0～ 2 6 0岁 ,平均 18 4岁。术中暴露峡部并清理缺损区的纤维组织 ,分别切除两侧 1 0～ 2 0mm骨质 ,暴露新鲜骨界面 ,间隙内植入髂骨块 ,以椎板下缘中线旁开 8mm为进钉点 ,向头端和外侧各 30°倾斜安装长度 35 0～ 4 5 0mm ,直径 3 5mm钛质拉力螺钉 ,穿越峡部缺损和植骨块直至穿透椎弓根的外上缘皮质并紧固。峡部缺损表面植入条状植骨条 ,采用高强度尼龙线在螺钉尾部和横突基底部间形成张力带结构 ,关闭切口并留置负压引流。手术后石膏腰围固定 2个月。　结果　手术平均时间为 (10± 5 5 )min ,失血量为 170ml,术后随访 12～ 36个月 ,平均 17个月 ,所有修复的 2 2个峡部均在术后 3个月愈合。　结论　峡部植骨修复拉力螺钉张力带固定治疗青少年下腰椎峡部裂是一种简单、安全、可靠的术式 ,结合了生物力学和生物学过程 ,具有创伤小和保留病变节段运动功能的优点。     

The stabilizing potential of anterior, posterior and combined techniques for the reconstruction of a 2-level cervical corpectomy model: biomechanical study and first results of ATPS prototyping

Clinical studies reported frequent failure with anterior instrumented multilevel cervical corpectomies. Hence, posterior augmentation was recommended but necessitates a second approach. Thus, an author group evaluated the feasibility, pull-out characteristics, and accuracy of anterior transpedicular screw (ATPS) fixation. Although first success with clinical application of ATPS has already been reported, no data exist on biomechanical characteristics of an ATPS-plate system enabling transpedicular end-level fixation in advanced instabilities. Therefore, we evaluated biomechanical qualities of an ATPS prototype C4–C7 for reduction of range of motion (ROM) and primary stability in a non-destructive setup among five constructs: anterior plate, posterior all-lateral mass screw construct, posterior construct with lateral mass screws C5 + C6 and end-level fixation using pedicle screws unilaterally or bilaterally, and a 360° construct. 12 human spines C3–T1 were divided into two groups. Four constructs were tested in group 1 and three in group 2; the ATPS prototypes were tested in both groups. Specimens were subjected to flexibility test in a spine motion tester at intact state and after 2-level corpectomy C5–C6 with subsequent reconstruction using a distractable cage and one of the osteosynthesis mentioned above. ROM in flexion–extension, axial rotation, and lateral bending was reported as normalized values. All instrumentations but the anterior plate showed significant reduction of ROM for all directions compared to the intact state. The 360° construct outperformed all others in terms of reducing ROM. While there were no significant differences between the 360° and posterior constructs in flexion–extension and lateral bending, the 360° constructs were significantly more stable in axial rotation. Concerning primary stability of ATPS prototypes, there were no significant differences compared to posterior-only constructs in flexion–extension and axial rotation. The 360° construct showed significant differences to the ATPS prototypes in flexion–extension, while no significant differences existed in axial rotation. But in lateral bending, the ATPS prototype and the anterior plate performed significantly worse than the posterior constructs. ATPS was shown to confer increased primary stability compared to the anterior plate in flexion–extension and axial rotation with the latter yielding significance. We showed that primary stability after 2-level corpectomy reconstruction using ATPS prototypes compared favorably to posterior systems and superior to anterior plates. From the biomechanical point, the 360° instrumentation was shown the most efficient for reconstruction of 2-level corpectomies. Further studies will elucidate whether fatigue testing will enhance the benefit of transpedicular anchorage with posterior constructs and ATPS.     

Systematic effects of surgical treatment of hip fractures: Gliding screw-plating vs intramedullary nailing

Aim

Numerous studies have been published regarding the comparison between intramedullary nail and the dynamic hip screw and plate for the fixation of intertrochanteric fractures in elderly patients. In this paper we present a comparative study of these two methods regarding their systemic effects on this group of patients.

Materials-methods

This is a randomized trial of 120 consecutive patients with an intertrochanteric fracture treated with either extramedullary fixation (dynamic hip screw and plate; DHS, Synthes-Stratec, Oberdorf, Switzerland) or intramedullary nail (Gamma nail, Stryker Howmedica, Freiburg, Germany and Endovis BA, Citieffe, Bologna, Italy).The parameters that we assessed pre-operatively, in addition to their demographics, included their mental state (MMSE), their nutritional and immune state and their pulmonary function. Intra-operatively we calculated the amount of radiation exposure, the amount of blood loss and the length of operative time for each procedure. Postoperatively we repeated the calculation of the mental and pulmonary state and the blood loss, during days 1, 3, and 10 and related them to the ease of the patient's mobilization.

Results

Decreased bleeding and post-operative pain, reduced post-operative morbidity and faster recovery of function were better but not significant in the group of intramedullary fixation (all p > 0.05). However, in the same group there were slightly more patients in whom the MMSE was falling, together with their pulmonary function, suggesting that this method probably predisposes to higher chances of pulmonary dysfunction and the possibility of pulmonary embolism.

Conclusion

We found no significant differences between the two methods of stabilization of these fractures regarding their systemic effects perioperatively. The classic dynamic hip screw can preserve its position as a safe and effective solution for these already vulnerable patients having sustained a trochanteric fracture against the novel intramedullary techniques.