Mechanical compression augments venous flow equal to intermittent pneumatic compression

Intermittent pneumatic compression is part of the current standard of care model for preventing venous thromboembolic events (VTE) after total joint arthroplasty. Pneumatic motors limit the rate of inflation resulting in bulky devices with uncomfortable sleeves that inhibited patient compliance and mobility. Nonpneumatic mechanical devices are an alternative for providing mobile, graded, intermittent, sequential, rapid, and monitorable compression posthospitalization. Fifteen healthy volunteers underwent mechanical compression using the Cirvo (Radial Medical, Mountain View, CA) as well as pneumatic compression with four commercially available systems (VenaFlow Elite, Kendall SCD Compression System, ActiveCare DVT, Vasculaire Compression System) and manual calf compression. Peak flow velocity (PFV) was measured by ultrasound of the femoral vein during compression and at baseline. Mechanical compression for 1 second resulted in a significant increase in femoral venous PFV to 107.8 ± 38.2 cm/s from 17.1 ± 4.7 cm/s at baseline (P < .001). The change in femoral venous PFV with mechanical compression for 1 second (90.7 ± 34.9 cm/s) was not statistically different from pneumatic compression from VenaFlow system (106.0 ± 35.6 cm/s, P = .124) and statistically lower than manual calf compression (115.5 ± 26.8 cm/s, P = .015). Pneumatic compression from the VenaFlow system produced the largest change in femoral venous PFV of all commercial pneumatic systems tested. Mechanical compression replicates or exceeds femoral venous PFV available from currently available intermittent pneumatic compression.     

周期性充气加压在下肢深静脉血栓治疗中的应用

[目的]探讨单独使用周期性充气加压装置应用于下肢深静脉血栓的疗效。[方法]对比研究2000年12月~2007年8月对52例骨科下肢深静脉血栓患者在溶栓或介入接触性溶栓术后用与不用周期性充气加压的疗效。病人分两组:第1组(32例)溶栓或导管介入接触性溶栓术后常规使用低分子肝素及华法林;第2组(20例)在第1组的基础上加用周期性充气加压,对比两组中需追加溶栓例数、症状开始缓解时间、第7 d肿胀消退程度及1个月后病变段静脉再通程度。[结果]第1组有3例需追加溶栓,第2组没有需追加溶栓者;第2组症状缓解快、肿胀消退明显、病变段静脉再通程度高。[结论]周期性充气加压在深静脉血栓的综合治疗中能发挥良好的效果。     

A prospective pilot study of thigh‐administered intermittent pneumatic compression in the management of hard‐to‐heal lower limb venous and mixed aetiology ulcers

This was a prospective observational pilot study of a unique intermittent pneumatic compression (IPC) device designed to be applied in the thigh region of the affected limb in patients with lower limb ulceration of both venous and mixed (venous and arterial) aetiologies. This compression system consists of a circumferential three‐chamber thigh garment and an electronic pneumatic compression pump operating over a repeated 4‐minute cycle. Patients were recruited from outpatient wound clinics. Those recruited were treated with standard therapy in addition to IPC, which was applied for 2 hours per day, and followed up for a total of 8 weeks. The primary objective of the study was to examine the effects of IPC on wound healing over an 8‐week period. The other objectives were to assess patients’ experiences of pain and the acceptability of IPC device. Twenty‐one patients were recruited, and wounds progressed towards healing in 95.24% (20/21) of the patients. Pain scores decreased in 83.33% (15/18) of the patients. Most patients felt that the thigh‐applied IPC device was comfortable and easy to apply and remove. The thigh‐administered IPC device can be recommended for use in routine clinical practice, especially when other treatment options are limited.     

Intermittent pneumatic soft tissue compression: Changes in periosteal and medullary canal blood flow

We previously demonstrated that the use of intermittent pneumatic soft tissue compression (IPC) treatment enhanced fracture healing in an animal model, but the exact mechanism remained unknown. The purpose of this study was to determine the local and remote effects of IPC treatment on blood flow within the medullary canal and outside the periosteum of mid‐tibial diaphysis. Blood flow was measured with a Laser Doppler blood flow meter in the lower limbs of 21 rabbits. Laser probes were inserted at three different sites of the mid‐diaphysis on the right tibia: in the medullary canal (n = 21), outside the periosteum on the lateral side (n = 11), and outside the periosteum on the medial side (n = 10). IPC was applied for 30 min through cuffs that were placed around the feet and the lower part of the calf. While applying IPC to the left leg, no changes in blood flow occurred on the right leg (remote changes). However, while applying IPC to the right leg, significant localized changes were found on the right leg, including 47 and 89% increases in total amount of blood flow outside the lateral and medial periosteum, respectively. Although an altered blood flow pattern was observed in the medullary canal, no significant change in total amount of blood flow was observed at this level. In summary, the present study demonstrated that the use of IPC in an intact bone model results in a significant local increase in total blood flow, with minimal measurable effects on the contralateral limb. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:570–577, 2008     

Changes in femoral vein blood flow velocity by intermittent pneumatic compression: calf compression device versus plantar-calf sequential compression device

Intermittent pneumatic compression has become widely used to prevent deep venous thrombosis potentially causing fatal pulmonary embolism. Although uniform compression has been commonly applied, a new method of sequential compression from plantar to calf has recently been developed. In this report, changes in maximum blood flow velocity in the femoral vein were compared with compression of only the calf uniformly and compression from plantar to calf sequentially in 10 healthy adult volunteers. A compression pressure of 60mmHg was applied for 5min, and the velocity was measured before and after this treatment by ultrasound echography. There was no statistically significant difference in the change in maximum velocity between calf compression and plantar-calf sequential compression. The maximum velocity increased significantly with both compressions. However, plantar-calf sequential compression tended to have a greater effect. Although the results did not demonstrate an advantage of plantar-calf sequential compression compared with calf compression only, if the former compression is applied for a long time, it may have a greater effect.     

压力梯度长袜和间歇充气装置预防恶性肿瘤患者术后下肢深静脉血栓形成的效果

目的 观察单纯应用压力梯度长袜（CS）或与间歇充气装置（IPC）联合使用预防恶性肿瘤患者术后下肢深静脉血栓（DVT）形成的效果及可能的机制。方法 胸科、泌尿外科、肝胆外科恶性肿瘤根治手术患者240例，随机分为4组：对照组、单纯CS组、CS＋IPC全程组、CS＋IPC术后组，每组60例。术后3～8d内行双下肢深静脉超声检查，记录DVT例数及血栓发生部位（大腿或小腿）。随机选择对照组和CS＋IPC全程组各15例患者，分别于术前、切皮后2h及术后24h各采集外周静脉血2ml，测定D-二聚体（D-D）、纤溶酶原激活物抗原（tPA-Ag）、纤溶酶原激活物抑制物（PAI）、血管性血友病因子（vWF）、凝血酶原时间（PT）和活化部分凝血活酶时间（APTT）。结果 术后3-8d对照组、CS＋IPC全程组、CS＋IPC术后组和单纯CS组DVT发生率分别为49．3％、15．0％、23．3％和30．0％（P〈0．05）。所有发生DVT患者中，除CS组发现1例近端DVT外，其余均为远端DVT。发生DVT患者年龄、卧床时间、危险因素个数等与未发生血栓患者相比差异有统计学意义（P〈0．05）。凝血，纤溶指标：与对照组比较，切皮后2h，CS＋IPC全程组vWF升高，D-D、tPA-Ag降低（P〈0．05），术后24h对照组和cs＋IPC全程组间D—D、vWF、tPA-Ag及PAI差异无统计学意义。结论 CS＋IPC全程或术后使用均能降低高危患者术后DVT的发生，其中CS＋IPC全程使用预防效果最好，可能与IPC增加纤溶活性有关。     

Effect of calf-thigh intermittent pneumatic compression device after total hip arthroplasty: comparative analysis with plantar compression on the effectiveness of reducing thrombogenesis and leg swelling

The purpose of this study was to evaluate the efficacy of two intermittent pneumatic compression devices as prophylaxis against intravascular coagulation and leg swelling following total hip arthroplasty. We studied 121 patients by assessing thrombogenesis using the D-dimer level before and after total hip arthroplasty. In addition, the patients postoperative swelling was evaluated by measuring the thigh and lower leg circumference. Altogether, 58 patients were assigned to the calf-thigh pneumatic compression group, and the other 63 were assigned to the plantar compression group; the two pneumatic compression devices were compared to evaluate which was more effective for reducing thrombogenesis. At 7 days postoperatively, the mean D-dimer levels of the calf-thigh compression group and the plantar compression group were 8.86 and 9.26µg/ml, respectively. There was no significant difference (P = 0.697) between the two groups. However, the increased ratio of the circumference of the thigh, which was compared after arthroplasty, averaged 1.22% in the calf-thigh compression group and 3.19% in the plantar compression group, which was significantly different (P 0.01). Calf-thigh pneumatic compression was found to be more effective than plantar compression for reducing thigh swelling during the early postoperative stage.     

全膝关节置换术后间歇充气压力装置使用开始时间研究

目的探讨全膝关节置换术患者术后早期使用间歇充气压力装置预防下肢深静脉血栓的效果及安全性。方法将91例行单侧全膝关节置换手术患者随机分为早期组44例、晚期组47例,术后两组均行常规抗凝治疗及护理;早期组术后返回病房当天行间歇充气压力装置治疗2h,以后每天2次,每次2h;晚期组术后1d开始行间歇充气压力装置治疗,频次与时间同早期组。结果两组出血量及术后各时段VAS评分比较,差异无统计学意义(均P0.05);早期组未发生DVT,晚期组4例(8.51%)发生DVT;早期组术后3d大腿肿胀程度显著轻于晚期组,术后3d、14d膝关节活动度显著大于晚期组(均P0.01)。结论全膝关节置换术后早期应用间歇充气压力装置辅助治疗,不会增加出血量及疼痛;可有效预防下肢深静脉血栓形成,减轻术肢肿胀及改善膝关节活动,有利于术侧肢体康复。     

Intermittent pneumatic foot compression can activate blood fibrinolysis without changes in blood coagulability and platelet activation

BACKGROUND: Intermittent pneumatic foot compression (IPC) is a useful technique for prophylaxis of peri-operative venous thromboembolism. The aim of this study was to determine the effect of IPC on blood coagulation/fibrinolysis and platelet function using a blood viscometer (Sonoclot) and a platelet aggregation monitor (WBA analyzer(TM)), respectively. Using the same blood samples, serum levels of tissue-type plasminogen activator (t-PA), thrombomodulin (TM) and activated protein C (APC) were also measured. METHODS: The soles and legs of each subject (n = 8) were compressed for 3 s (130 mmHg) at a 0.3-Hz interval using an IPC device. Parameters were measured 2 min before and at the end of 60-min compression. RESULTS: Parameters of the Sonoclot time-to-peak were shortened and clot retraction rate was increased significantly by IPC, whereas the other parameters did not change. These results indicate that IPC can activate blood fibrinolysis but not coagulability. A parameter of the WBA analyzer PATI (platelet aggregatory threshold index) did not change, indicating that IPC cannot activate platelet function per se. The concentration of t-PA decreased slightly but significantly. A decrease in the concentration of t-PA can lead to activation of fibrinolysis. Other humoral parameters did not change, indicating that IPC has no effect on endothelial function. Although neither blood coagulability nor platelet function were affected by IPC, fibrinolytic activity increased slightly, probably by activation of t-PA function. CONCLUSION: IPC is useful for prophylaxis for thromboembolism by activation of blood fibrinolysis as well as inhibition of blood stasis.     

周期性充气加压预防髋关节置换术后下肢深静脉血栓的效果

目的比较观察单纯使用周期性充气加压系统（IPCS）与低分子肝素预防人工全髋关节置换术后下肢深静脉血栓（DVT）的临床效果。方法选取61例单侧初次全髋关节置换术的患者,随机分成IPCS组和低分子肝素组。低分子肝素组从术前第1天开始应用低分子肝素0．2ml/d,皮下注射。IPCS组术后立即使用IPCS治疗,每天5h,术后14d内持续使用。每个研究对象分别于术前1d、术后第3、7d各进行下肢深静脉超声、血浆D-二聚体、P-选择素测定。结果肝素组和IPCS组发生DVT分别为2例和3例;两组均未出现有临床症状的肺栓塞;两组临床效果差异无显著性（P〉0．05）。结论下肢IPCS系统对全髋关节置换术后的DVT形成具有很好的预防作用,是一种安全、简便的物理疗法。     

Effect of intermittent pneumatic compression with different inflation pressures on the distal microvascular responses of the foot in people with type 2 diabetes mellitus

Intermittent pneumatic compression (IPC) is commonly used to improve peripheral circulation of the lower extremity. However, its therapeutic dosage for people with type 2 diabetes mellitus (DM) at risk for ulcers is not well established. This study explored the effect of IPC with different inflation pressures on the distal microvascular responses of the foot in people with type 2 DM. Twenty‐four subjects with and without DM were recruited. Three IPC protocols with inflation pressures of 60, 90, and 120 mmHg were applied to the foot. The foot skin blood flow (SBF) responses were measured by laser Doppler flowmetry during and after IPC interventions. Results show that all three IPC interventions significantly increased foot SBF of IPC stage in healthy subjects, but only 90 and 120 mmHg IPC significantly improved SBF in diabetic subjects. IPC with 90 and 120 mmHg showed a greater effect than 60 mmHg in both groups, but 120 mmHg IPC was more effective for diabetic subjects. This study demonstrates that 90 and 120 mmHg are effective dosages of IPC for improving blood flow in healthy people, and 120 mmHg IPC may be more suitable for people with type 2 DM.     

超早期间歇充气加压预防老年转子间骨折术后下肢深静脉血栓形成的病例对照研究

目的:评价超早期间歇充气加压(intermittent pneumatic compression,IPC)治疗预防老年股骨转子间骨折术后下肢深静脉血栓形成的疗效。方法:对2008年5月至2010年5月收治的80例老年股骨转子间骨折患者分为超早期组和术后组,各40例,其中超早期组男21例,女19例,年龄67～86岁,平均(76.4±13.27)岁;术后组男26例,女14例,年龄68～89岁,平均(75.8±12.71)岁。超早期组为术前3d开始使用IPC,术后组术后当天开始使用IPC。分别测定患者术前第3天,术后第3、7、14天血清D-二聚体(D-D)浓度。术前第3天,术后第3、14天通过双下肢深静脉超声检查患者DVT发生情况。记录两组患者的围手术期出血量。结果:两组患者术前第3天血清D-D浓度及双下肢DVT发生情况差异无统计学意义,两组患者围手术期出血量差异无统计学意义。超早期组术后第3、7天血清D-D浓度分别为(351.00±104.34)、(412.31±106.95)μg/ml,比术后组(419.34±145.38)、(509.16±146.05)μg/ml低;术后第14天,两组患者血清D-D浓度差异无统计学意义。两组患者术后第3天DVT发生率分别为7.5%、12.5%,差异无统计学意义;术后第14天术后组DVT发生率为22.5%,高于超早期组。结论:与术后开始使用IPC相比,超早期使用IPC在不增加老年转子间骨折围手术期出血量的情况下可降低患者术后血清D-D浓度水平,并能降低DVT的发生率。     

应用间歇性气体压缩装置预防人工髋关节置换术下肢深静脉血栓形成

目的探讨对有高出血风险患者应用间歇性气体压缩装置预防人工髋关节置换术后下肢深静脉血栓形成的效果及护理要点。方法2010年3月至2013年1月,对有高出血风险、需要行人工全髋关节置换术或人工股骨头置换术的患者58例,采用基本预防和下肢间歇性气体压缩装置物理预防。主要观察双下肢肢体颜色、肿胀、疼痛等病症,双下肢彩色多普勒超声检查结果。结果58例有高出血风险患者人工髋关节置换术后,其中5例发生患侧肢体疼痛、肿胀,3例无症状、体征,经彩色多普勒超声检查提示深静脉血栓形成共8例,发生率13．65％。结论有高出血风险患者人工髋关节置换术后应用间歇性气体压缩装置,正确使用、仔细观察并有效解决应用中的问题,能有效地预防和减少下肢深静脉血栓形成。     

间歇性充气加压和新型敷料联合应用治疗下肢慢性静脉性溃疡

目的探讨间歇性充气加压(IPC)和新型敷料联合应用治疗下肢慢性静脉性溃疡的临床疗效。方法 69例(79条患肢)慢性下肢静脉性溃疡的患者随机分为两组:治疗组35例(39条患肢)采用手术加IPC和新型敷料治疗;对照组34例(40条患肢)采用手术加传统敷料方法治疗。结果治疗30天后,治疗组治愈率为91.4%,对照组为70.6%;两组比较差异有统计学意义(P<0.05)。结论 IPC和新型敷料联合应用对下肢慢性静脉性溃疡疗效可靠,值得临床推广和应用。     

Intermittent pneumatic compression enhances neurovascular ingrowth and tissue proliferation during connective tissue healing: a study in the rat.

Intermittent pneumatic compression (IPC) is a treatment method to decrease venous stasis and stimulate blood flow. Recently, it was hypothesized that IPC may exert positive effects on tissue healing, a process highly dependent upon adequate circulation. In this study, we investigated the effects of daily 1-h IPC treatment during 2 and 4 weeks post-rat Achilles tendon rupture. The tendons were subjectively and semiquantitatively analyzed for collagen organization, fibroblast density, angiogenesis, and the occurrence of sensory neuropeptides, substance P (SP) and calcitonine gene related peptide (CGRP), as well as for a nerve regeneration marker, growth associated protein 43 (GAP-43). After 2 weeks of treatment, fibroblast density increased by 53% (p = 0.0004), vessel density by 64% (p = 0.022), and the occurrence of SP by 110% (p = 0.047) and CGRP by 47% (p = 0.0163) compared to untreated controls. Following 4 weeks of treatment, both the occurrence of sensory neuropeptides and the vessel density remained significantly higher (p < 0.05), whereas fibroblast density returned to normal. However, at 4 weeks the treated tendons displayed a higher degree of organized parallel collagen fibers, a sign of increased maturation. Daily IPC treatment improves neurovascular ingrowth and fibroblast proliferation in the healing tendon and may accelerate the repair process.     

间歇充气加压对直肠癌术后凝血功能和下肢深静脉血流动力学的影响

目的探讨间歇充气加压（IPC）对直肠癌患者术后凝血功能和下肢深静脉血流动力学的影响,以及对下肢深静脉血栓（DVT）的预防作用。方法将120例直肠癌根治手术患者按随机数字表法随机分为IPC组和对照组各60例,对照组按常规术后处理．IPC组在常规术后处理的基础上使用IPC。分别于术前及术后1、3、5和7d检测凝血酶原时间（PTT）、活化部分凝血活酶时间（APITr）、纤维蛋白原（FIB）、凝血酶原国际标准化值（INR）及血浆D一二聚体（D—D）含量;用彩色多普勒超声检查髂外、股及胭静脉管径和血流速度,计算平均血流速度（v）及血流量（Q）。结果对照组发生下肢DVT8例（13．3％）,IPC组发生1例（1．7％）,差异有统计学意义（P〈0．05）。两组患者术前frr、APTT、INR、FIB和D—D差异均无统计学意义（均P〉0．05）;术后1d,两组frr、APTT、INR与术前比较,差异均无统计学意义（均P〉0．05）,而FIB和D．D较术前显著升高（P〈0．05）,两组问差异无统计学意义（P〉0．05）。随着术后时间延长,两组PT逐步缩短（P〈0．05）,APTr和INR均无显著变化（P〉0．05）,FIB和D—D逐步升高（P〈0．05）,但两组间差异无统计学意义（P〉O．05）。术后1、3、5和7d,对照组下肢深静脉平均血流速度及血流量均小于IPC组,差异均有统计学意义（均P〈0．05）。结论间歇充气加压能改善直肠癌术后患者下肢深静脉血流动力学指标,有效预防术后下肢DVT的发生,是一种安全而简便的物理疗法。     

A single arm prospective feasibility study evaluating wound closure with a unique wearable device that provides intermittent plantar compression and offloading in the treatment of non-healing diabetic foot ulcers

The incidence and economic burden of diabetic foot ulcers continues to rise throughout the world. In this prospective study, a unique device designed to offload the wound, enhance circulation and monitor patient compliance was evaluated for safety and efficacy. The device provides offloading and intermittent plantar compression to improve the pedal flow of oxygenated blood and support wound healing while recording patient use. Ten patients with non-healing diabetic foot ulcers UTgrade 1A/Wagner grade 1 were treated weekly for up to 12 weeks. The primary endpoint was complete wound closure at 12 weeks, and secondary endpoints included healing time, percent area reduction and changes in pain using the visual analogue pain scale. Eight out of ten wounds healed within 12 weeks(80%), and the mean healing time was 41 days(95% CI:24.3–58.3). The percent area reduction was 75(SD:53.9). The baseline visual analogue pain scale was 4.5(2.9) as compared with 3.3(3.4) at end of study. No device-related or serious adverse events were reported. This unique intermediate plantar compression and offloading device may be considered as an alternative for safe and effective for treatment of non-healing diabetic foot ulcers. During treatment, wound healing was significantly accelerated, and pain was improved. Larger randomised controlled trials are underway to validate these early findings.     

Effects of intermittent pneumatic compression of the calf and thigh on arterial calf inflow: a study of normals, claudicants, and grafted arteriopaths

BACKGROUND: Recent data indicate that intermittent pneumatic compression (IPC) of the foot may offer benefits in patients with intermittent claudication exceeding those of standard medications approved by the Food and Drug Administration. IPC of the foot (IPC(foot)) and calf (IPC(calf)) increases flow velocity in infrainguinal arterial bypass grafts and thus may prevent arterial thrombosis. Our aim was to evaluate the acute effects of IPC of the thigh (IPC(thigh)), IPC(calf), and IPC of the thigh and calf (IPC(calf + thigh)) in healthy controls, claudicants, and arteriopaths who have undergone infrainguinal bypass grafting for critical or subcritical limb ischemia. METHODS: Sixteen limbs of normals (group A), 17 limbs of claudicants (group B), and 16 limbs of arteriopaths (group C) who had undergone infrainguinal autologous revascularization were studied. Blood flow was measured in the limbs of normals and claudicants in the popliteal artery and in the grafts of revascularized limbs by using duplex ultrasonography. Mean velocity (mV), peak systolic velocity, end diastolic velocity (EDV), pulsatility index (PI), and volume flow (Q) were measured in the sitting position at rest and within 10 seconds from the delivery of IPC(thigh), IPC(calf), and IPC(calf + thigh), IPC was delivered at maximum inflation and deflation pressures of 120 mm Hg and 0 mm Hg, respectively; inflation and deflation times of 4 and 16 seconds, respectively; and a proximal inflate delay of 1 second (calf compression preceding that of thigh). RESULTS: In all 3 groups with all IPC modes, the Q, mV, and EDV increased while PI decreased (P <.05). IPC(thigh) was less effective than IPC(calf), but still increased Q (by 114%, 57%, and 59.8% in groups A, B, and C, respectively) and EDV, while decreasing PI in all 3 groups (P <.05). IPC(calf + thigh) was the most efficient mode, generating an increase in the median Q of 424% in controls, 229% in claudicants, and 317% in grafted arteriopaths. The addition of IPC(thigh) to IPC(calf) increased the mV and Q in group A (P < or = .044); the mV, Q, and EDV in group B (P < or = .03), and mV and PI by 24% and -27% in group C, respectively. CONCLUSIONS: IPC applied to the thigh, either alone or in combination with IPC(calf), generates native arterial and infrainguinal autologous graft flow enhancement. The paucity of conservative methods available for lower limb blood flow augmentation may allow IPC of the lower limb to emerge as a reliable, noninvasive therapeutic option, ameliorating claudication and assisting infrainguinal bypass graft flow. IPC(thigh) adds to the armamentarium of currently known IPC options (foot or calf) promoting its applicability and efficacy.     

Effect of intermittent cyclic preloads on the response of articular cartilage explants to an excessive level of unconfined compression

Mechanical loading of articular cartilage can influence chondrocyte metabolism and lead to alterations in cartilage matrix composition. Most previous studies have focused on the effect of cyclic loading on cartilage mechanical properties and proteoglycan synthesis. However, the role of proteoglycans synthesized from cyclically loaded cartilage in response to an acute overload has not been elucidated. Therefore, we conducted studies where low intensity, intermittent cyclic loading was applied to chondral explants prior to an acute unconfined compression on the tissue. The chondral explants were randomly assigned to three groups: 7, 14, and 21 days of 10 cycles of 0.2 Hz sinusoidal loading at 0.5 MPa followed by an unloaded interval of 3,600 s. All explants were then taken to 25 MPa of unconfined compression. Biochemical assays were conducted to determine the tissue proteoglycan and hydroxyproline contents. The results showed cyclic preloading increased the proteoglycan content and mechanically stiffened the explants, making them more resistant to matrix damage and cell death under 25 MPa of unconfined compression up to 14 days. After 21 days of cyclic loading, however, the explants lost compressive stiffness and suffered more extensive damage in the unconfined compression test. This study investigated the role of cyclic loading in response of chondral explants to a potentially damaging, acute overload. In the long term, these types of studies may help understand the role of preconditioning of articular cartilage for in vitro or even in vivo studies of blunt force trauma to a joint. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res