中文摘要
關節內負壓在關節內提供關節被動穩定度。但相對於大關節，掌指關節的關節內壓至今沒有完整被研究。在手持式產品日益增加下，手部關節內壓相關研究的重要性也隨之增加。關節體積受限效應(limited joint volume effect)是通常用來描述關節內壓提供滑液囊關節穩定度的現象。但是目前關節內壓與關節體積變化的相關性還沒被量化。本研究的目的為探討關節內負壓在掌指關節受到軸向力時關節內負壓對關節穩定度的貢獻。此外也要量化掌指關節受到牽張力時關節內壓與關節體積改變的相關性。
本研究的樣本為新鮮的掌指關節。發展出一個可裝置於微電腦斷層掃描儀的自製負載裝置去量測在掌指關節受軸向牽張力時的位移，與經由斷層掃描影像量測關節體積的改變。然後每個樣本在關節囊完整(intact)與通氣(vented)時，也在材料試驗機上施與負載。最大的牽張負載力為16公斤。此外負載、位移、牽張力負載關節內壓等資料由材料試驗機與壓力感測器獲得。關節內壓與負載、位移、關節總體積改變(total volume)、頸縮體積(necking volume)等參數進行相關性分析。根據實驗建立一個有限元素模型，探討關節內壓的存在與否對掌指關節的影響。模擬後關節囊變形的結果再與實驗中相同牽張力下微電腦斷層掃描影像中關節囊形變進行比較。
將掌指關節受到牽張力的負載與位移的曲線分成三個區域：趾區 (toe-region)，過度區(transition region)(以交點(cross-point)表示)，與終端區(terminal region)。結果顯示關節囊完整與通氣的情況下，在交點的位移量與16公斤的位移量兩者均有顯著差異。在關節囊完整與通氣的情況下，交點的位移量分別為3.44 ± 0.82 mm 與 4.01 ± 0.81 mm (p < 0.001)。在關節囊完整與通氣的情況下，在最大負載16公斤時的位移量分別為4.60 ± 0.80 mm與5.22 ± 0.97 mm (p < 0.001)。但在關節囊完整與通氣的情況下，最大16公斤時與交點時的位移差分別為1.16 ± 0.26 mm 與 1.20 ± 0.33 mm並無統計上顯著差異(p = 0.112)。且在關節囊完整與通氣的情況下，在終端區的勁度分別為12.59 ± 2.53 kg/mm 與 12.28 ± 2.70 kg/mm也沒有統計上的差異(p = 0.124)。此外，在交點前，關節內壓下降了總量的45% ~ 80%，此時掌指關節指承受了最大16公斤負載中的前1-2公斤。這些結果建議關節內壓在掌指關節受到牽張力時的關節穩定度貢獻大概在交點前的初始階段。
關節內壓與關節總體積改變(r = -0.982 ± 0.015)、頸縮體積 (r = -0.951 ± 0.025)、位移(r = -0.963 ± 0.029)均呈現高度(負)線性相關。而關節內壓與負載(r = -0.792 ± 0.151)呈現中度線性相關。此線性相關反映出關節內壓與關節體積受限效應的關係。在有限元素模擬方面，掌指關節在施與16公斤軸向力與關節內負壓時的軸向位移量，相似於實驗中獲得的軸向位移量。然而，在關節囊的徑向變形量(頸縮效果)，模擬結果(1.88mm)與實驗結果(5mm)卻有很大不同。這或許是由於模擬中構成關節囊材料與實驗真實軟組織材料不同所致。
本研究獲得下列幾項結論：關節內壓對掌指關節穩定度貢獻大部分在交點之前，大概是總16公斤牽張力中的前1-2公斤。因此在掌指關節受到牽張力時關節內壓提供初始階段的穩定度，關節囊提供受力後期的穩定度。關節內壓與關節總體積改變和頸縮體積皆呈現高度線性負相關。因此以受限體積效應來解釋關節內壓對關節穩定度的貢獻是合乎邏輯的。

Negative intra-articular pressure (IAP) is a passive stabilizer during joint movement. In contrast to that of large joints, the IAP within the metacarpophalangeal (MCP) joint has not been well studied. The IAP in hand joints would become more important as the increasing demand of hand held devices. The limited joint volume effect is often used to describe the phenomenon of IAP on the stability the synovial joint. But the relation of the IAP and joint volume change has never been quantified. The objective of this study was to evaluate the biomechanical effects of the IAP of MCP joint in terms of load-displacement relation under long-axis distraction. Moreover, the quantitative relationship between IAP and joint volume change under joint distraction was also studied.
Fresh MCP joints specimens were used in this study. A custom-made loading device compatible with micro computed tomography (CT) was developed to measure the displacement and joint volume change, through CT images, under distraction load. Each specimen was also loaded using the material testing machine under intact and vented conditions of the joint capsule. The maximum distraction load for all specimens was 16kg. In addition to load-displacement data, the IAP under distraction load, thru material testing machine, was obtained with a pressure transducer. The correlation of the IAP with the load, displacement, volume change, and necking volume was analyzed. A finite element model, based on the experimental loading, was established to simulate the effect of IAP on MCP joint. The simulated deformation of the capsule was compared to the corresponding experimental outcomes including deformation from micro CT images.
The result shown that a typical load-displacement curve of a MCP joint under distraction force can be divided into three regions: toe-region, transition region (represented by the cross-point), and terminal region. Significant difference was found in the displacement at the cross-point (p < 0.001) and at the maximum load (16 kg) (p < 0.001) between intact and vented conditions. The displacements at cross-point were 3.44 ± 0.82 mm and 4.01 ± 0.81 mm for the intact and vented conditions, respectively. The displacements at maximum load were 4.60 ± 0.80 mm and 5.22 ± 0.97 mm for the intact and vented conditions, respectively. The displacement differences at the cross-point and 16 kg load were similar between the intact (1.16 ± 0.26 mm) and vented (1.20 ± 0.33 mm) conditions (p = 0.112). The stiffness values at the terminal range were not different between the intact (12.59 ± 2.53 kg/mm) and vented (12.28 ± 2.70 kg/mm) conditions (p = 0.124). Moreover, most of the IAP drops, range from 45% to 80%, occurred before the cross-point which bears only 1 to 2 kg of the total 16 kg distraction load. All these results suggested that the effect of axial distraction on IAP is expressed mostly at the initial stage, i.e. before the cross-point of the load-displacement relation.
Highly significant negative linear correlations were found between IAP and total volume change (r = -0.982 ± 0.015), necking volume (r = -0.951 ± 0.025), and displacement (r = -0.963 ± 0.029) for individual specimens. Intermediate linear correlations were found between the IAP and load (r = -0.792 ± 0.151). These results appear to reflect a relation between IAP and limited joint volume effect. For the finite element simulation, the axial displacement matched the corresponding experiment under the 16 kg axial loading when the negative IAP was applied. However, large difference was observed on the radial deformation of the joint capsule, necking effect, between the simulation (1.88 mm) and experiment (5 mm) outcomes. This might due to the constituting material model employed for the joint capsule.
In conclusion, the contribution of IAP to the stability of the MCP joint was demonstrated mostly before the cross-point, in the initial 1 to 2 kg of the total 16 kg distraction load. The IAP provides the stability at the initial stage while the joint capsule provides the stability in the late stage for MCP joint under distraction load. Highly negative linear correlation was found between IAP and total volume change as well as necking volume. The concept of the “limited joint volume effect” might be a logical rationale for the role of IAP in joint stabilization.

References

E Speed controller. (http://www.oetsindia.com/espeedc.htm)
Load cell (http://www.transducertechniques.com/load-cell.aspx)

Object stages for in situ examination: MATERIAL TESTING STAGE. (http://www.skyscan.be/products/stages.htm)

Stryker Intra-Compartmental Pressure Monitor (http://www.stryker.com/en-us/products/OREquipmentConnectivity/GeneralMultiSpecialtyEquipment/PressureMonitors/IntraCompartmentalPressureMonitor/index.htm)

Thomas AIR-PAC Model T-617HDN Electric Air Compressor. (http://cfpwarehouse.com/shopsite_sc/store/html/T617HDN.html)

Butz, K.D., Merrell, G., Nauman, E.A., 2012. A biomechanical analysis of finger joint forces and stresses developed during common daily activities. Computer methods in biomechanics and biomedical engineering 15, 131-140.

Castellanos, J., Axelrod, D., 1990. Effect of habitual knuckle cracking on hand function. Ann Rheum Dis 49, 308-309.

Chang, J.H., Hsu, A.T., Lee, S.J., Chang, G.L., 2004. Immediate effect of thermal capsulorrhaphy on glenohumeral joint mobility. Clin Biomech (Bristol, Avon) 19, 572-578.

Deweber, K., Olszewski, M., Ortolano, R., 2011. Knuckle cracking and hand osteoarthritis. Journal of the American Board of Family Medicine : JABFM 24, 169-174.

Evans, S.P., Parr, W.C.H., Clausen, P.D., Jones, A., Wroe, S., 2012. Finite element analysis of a micromechanical model of bone and a new 3D approach to validation. J Biomech 45, 2702-2705.

Gaffney, K., Williams, R.B., Jolliffe, V.A., Blake, D.R., 1995. Intraarticular Pressure Changes in Rheumatoid and Normal Peripheral Joints. Ann Rheum Dis 54, 670-673.

Gibb, T.D., Sidles, J.A., Harryman, D.T., Mcquade, K.J., Matsen, F.A., 1991. The Effect of Capsular Venting on Glenohumeral Laxity. Clin Orthop Relat R, 120-127.

Goddard, N.J., Gosling, P.T., 1988. Intra-articular fluid pressure and pain in osteoarthritis of the hip. J Bone Joint Surg Br 70, 52-55.

Guo, X., Fan, Y.B., Li, Z.M., 2009. Effects of dividing the transverse carpal ligament on the mechanical behavior of the carpal bones under axial compressive load: A finite element study. Med Eng Phys 31, 188-194.

Habermeyer, P., Schuller, U., Wiedemann, E., 1992. The intra-articular pressure of the shoulder: an experimental study on the role of the glenoid labrum in stabilizing the joint. Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International

Arthroscopy Association 8, 166-172.
Howe, A., Thompson, D., Wright, V., 1985. Reference values for metacarpophalangeal joint stiffness in normals. Ann Rheum Dis 44, 469-476.

Hurschler, C., Wulker, N., Mendila, M., 2000. The effect of negative intraarticular pressure and rotator cuff force on Glenohumeral translation during simulated active elevation. Clin Biomech 15, 306-314.

Itoi, E., Motzkin, N.E., Browne, A.O., Hoffmeyer, P.,
Morrey, B.F., An, K.N., 1993. Intraarticular Pressure of the Shoulder. Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association 9, 406-413.

Jawed, S., Gaffney, K., Blake, D.R., 1997. Intra-articular pressure profile of the knee joint in a spectrum of inflammatory arthropathies. Ann Rheum Dis 56, 686-689.

Jayson, M.I., Dixon, A.S.J., 1970a. Intra-articular pressure in rheumatoid arthritis of the knee. I. Pressure changes during passive joint distension. Ann Rheum Dis 29, 261-265.

Jayson, M.I., Dixon, A.S.J., 1970b. Intra-articular pressure in rheumatoid arthritis of the knee. II. Effect of intra-articular pressure on blood circulation to the synovium. Ann Rheum Dis 29, 266-268.

Jayson, M.I., Dixon, A.S.J., 1970c. Intra-articular pressure in rheumatoid arthritis of the knee. III. Pressure changes during joint use. Ann Rheum Dis 29, 401-408.

Karas, S.G., Creighton, R.A., DeMorat, G.J., 2004. Glenohumeral volume reduction in arthroscopic shoulder reconstruction: A cadaveric analysis of suture plication and thermal capsulorrhaphy. Arthroscopy-the Journal of Arthroscopic and Related Surgery 20, 179-184.

Kumar, V.P., Balasubramaniam, P., 1985. The Role of Atmospheric-Pressure in Stabilizing the Shoulder - an Experimental-Study. J Bone Joint Surg Br 67, 719-721.

Lubowitz, J., Bartolozzi, A., Rubinstein, D., Ciccotti, M., Schweitzer, M., Nazarian, L., Lombardi, J., Dellose, S., Landsdorf, A., Miller, L., 1996. How much does inferior capsular shift reduce shoulder volume? Clin Orthop Relat R, 86-90.

Martini, F.H., Timmons, M.J., 1995. Human Anatomy. Prentice Hall, Englewood Cliffs, New Jersey, pp207-208.

Merry, P., Williams, R., Cox, N., King, J.B., Blake, D.R., 1991. Comparative study of intra-articular pressure dynamics in joints with acute traumatic and chronic inflammatory effusions: potential implications for hypoxic-reperfusion injury. Ann Rheum Dis 50, 917-920.

Minami, A., An, K.N., Cooney, W.P., 3rd, Linscheid, R.L., Chao, E.Y., 1985. Ligament stability of the metacarpophalangeal joint: a biomechanical study. The Journal of hand surgery 10, 255-260.

Nitzan, D.W., 1994. Intraarticular Pressure in the Functioning Human Temporomandibular-Joint and Its Alteration by Uniform Elevation of the Occlusal Plane. J Oral Maxil Surg 52, 671-679.

Phil, S., 2007. Vive le difference: Micro-CT imaging of natural and enhanced tissue contrast in biomedical research.
Pylios, T., Shepherd, D.E.T., 2007. Biomechanics of the normal and diseased metacarpophalangeal joint: Implications on the design of joint replacement implants. J Mech Med Biol 7, 163-174.

Randall, T., Portney, L., Harris, B.A., 1992. Effects of joint mobilization on joint stiffness and active motion of the metacarpal-phalangeal joint. The Journal of orthopaedic and sports physical therapy 16, 30-36.

Resnik, C.S., Fronek, J., Frey, C., Gershuni, D., Resnick, D., 1984. Intra-articular pressure determination during glenohumeral joint arthrography. Preliminary investigation. Investigative radiology 19, 45-50.

Soto-Hall, R., Johnson, L.H., Johnson, R.A., 1964. Variations in the Intra-Articular Pressure of the Hip Joint in Injury and Disease. A Probable Factor in Avascular Necrosis. The Journal of bone and joint surgery. American volume 46, 509-516.

Vegter, J., 1987. The influence of joint posture on intra-articular pressure. A study of transient synovitis and Perthes' disease. J Bone Joint Surg Br 69, 71-74.
Watson, P., Hamilton, A., Mollan, R., 1989. Habitual joint cracking and radiological damage. BMJ 299, 1566.

Wu, C.C., 2008. Biomechanical analysis of elbow end-feel test in supination, pronation, neutral positions., Department of Physical Therapy. National Cheng Kung University, Taiwan.

Yamamoto, N., Itoi, E., Tuoheti, Y., Seki, N., Abe, H., Minagawa, H., Shimada, Y., Okada, K., 2006. The effect of the inferior capsular shift on shoulder intra-articular pressure - A cadaveric study. Am J Sport Med 34, 939-944.

Yung, P., Unsworth, A., Haslock, I., 1986. Measurement of stiffness in the metacarpophalangeal joint: the effects of physiotherapy. Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics 7, 147-156.