Robert Kraemer

Achilles Tendon and Paratendon Microcirculation in Midportion and Insertional Tendinopathy in Athletes

Background Neovascularisation can be detected qualitatively by Power Doppler in Achilles tendinopathy. Quantitative data regarding tendon microcirculation have not been established and may be substantial. Purpose To assess the microcirculation of the Achilles tendon and the paratendon in healthy volunteers as well as in athletes with either midportion or insertional tendinopathy. Study Design Cohort study; Level of evidence, 2. Methods In 66 physically active volunteers, parameters of Achilles tendon and paratendon microcirculation, such as tissue oxygen saturation, relative postcapillary venous filling pressures, and microcirculatory blood flow, were determined at rest at 2-mm and 8-mm tissue depths. Forty-one patients never had Achilles pain (25 men, 27 ± 8 years), 14 patients had insertional pain (7 men, 29 ± 8 years), and 11 patients had midportion tendinopathy (7 men, 38 ± 13 years, not significant). Results Achilles tendon diameter 2 cm and 6 cm proximal to the insertion was increased in symptomatic tendons. Compared with the uninvolved opposite tendon, deep microcirculatory blood flow was significantly elevated at insertional (160 ± 79 vs 132 ± 42, P<. 05) as well as in midportion tendinopathy (150 ± 74 vs 119 ± 34, P<. 05). The microcirculation in the uninvolved opposite tendon and the normal athlete controls were not significantly different from each other (132 ± 42 insertional asymptomatic vs 119 ± 34 mid-portion vs 120 ± 48 healthy tendon). Insertional paratendon deep microcirculatory flow was elevated in all groups, whereas tissue oxygen saturation and relative postcapillary venous filling pressures were not significantly different. Conclusion Microcirculatory blood flow is significantly elevated at the point of pain in insertional and midportion tendinopathy. Postcapillary venous filling pressures are increased at both the midportion Achilles tendon and the midportion paratendon, whereas tissue oxygen saturation is not different among the studied groups. We found no evidence of an abnormal microcirculation of the asymptomatic limb in Achilles tendinopathy.

A Soccer-Specific Balance Training Program for Hamstring Muscle and Patellar and Achilles Tendon Injuries: An Intervention Study in Premier League Female Soccer

Background A soccer-specific balance training has been shown to decrease injury incidence of the anterior cruciate ligament and ankle sprains in randomized controlled trials. However, hamstring injuries and tendinopathy remain significant issues in soccer. Hypothesis Proprioceptive training can reduce the incidence of hamstring muscle injuries and tendinopathy in elite soccer. There is a dose-effect relationship between balance training duration and injury incidence. Study Design Cohort study; Level of evidence, 3. Methods Twenty-four elite female soccer players (body mass index, 21.7 ± 1.2; age, 21 ± 4 years) of a German premier league soccer team were prospectively included. Starting in January 2004, an additional soccer-specific proprioceptive multistation training was initiated over 3 years. Injury data/1000 hours of exposure with documentation of all occurred injuries, detailed training, and match exposure data as well as time loss data were 100% complete. Results At the end of the 3-year proprioceptive balance training intervention, noncontact hamstring injury rates were reduced from 22.4 to 8.2/1000 hours (P = .021), patellar tendinopathy from 3.0 to 1.0/1000 hours (P = .022), and Achilles tendinopathy from 1.5 to 0.0/1000 hours (P = .035). There was no effect of balance training on contact injuries. Mean time loss of all assessed injuries significantly decreased from 14.4 days during the control period to 1.5 days during intervention periods (P = .003). The more minutes of balance training performed, the lower the rate of overall injuries (r = −0.185, P = .001), hamstring injuries (r = −0.267, P = .003), patellar tendinopathy (r = −0.398, P = .02), and gastrocnemius strains (r = −0.342, P = .002). Conclusion Soccer-specific balance training (protective balancing) can reduce noncontact hamstring injuries and patellar and Achilles tendinopathy. A dose-effect relationship between duration of balance training and injury incidence is evident. A proprioceptive training program reduced the rehabilitation time in noncontact injuries, which warrants further investigation.

Acute effects of remote ischemic preconditioning on cutaneous microcirculation - a controlled prospective cohort study

BackgroundTherapeutic strategies aiming to reduce ischemia/reperfusion injury by conditioning tissue tolerance against ischemia appear attractive not only from a scientific perspective, but also in clinics. Although previous studies indicate that remote ischemic intermittent preconditioning (RIPC) is a systemic phenomenon, only a few studies have focused on the elucidation of its mechanisms of action especially in the clinical setting. Therefore, the aim of this study is to evaluate the acute microcirculatory effects of remote ischemic preconditioning on a distinct cutaneous location at the lower extremity which is typically used as a harvesting site for free flap reconstructive surgery in a human in-vivo setting.MethodsMicrocirculatory data of 27 healthy subjects (25 males, age 24 ± 4 years, BMI 23.3) were evaluated continuously at the anterolateral aspect of the left thigh during RIPC using combined Laser-Doppler and photospectrometry (Oxygen-to-see, Lea Medizintechnik, Germany). After baseline microcirculatory measurement, remote ischemia was induced using a tourniquet on the contralateral upper arm for three cycles of 5 min.ResultsAfter RIPC, tissue oxygen saturation and capillary blood flow increased up to 29% and 35% during the third reperfusion phase versus baseline measurement, respectively (both p = 0.001). Postcapillary venous filling pressure decreased statistically significant by 16% during second reperfusion phase (p = 0.028).ConclusionRemote intermittent ischemic preconditioning affects cutaneous tissue oxygen saturation, arterial capillary blood flow and postcapillary venous filling pressure at a remote cutaneous location of the lower extremity. To what extent remote preconditioning might ameliorate reperfusion injury in soft tissue trauma or free flap transplantation further clinical trials have to evaluate.Trial registrationClinicalTrials.gov: NCT01235286

Achilles tendon suture deteriorates tendon capillary blood flow with sustained tissue oxygen saturation – an animal study

BackgroundTreatment of ruptured Achilles tendons currently constitutes of conservative early functional treatment or surgical treatment either by open or minimal invasive techniques. We hypothesize that an experimental Achilles tendon suture in an animal model significantly deteriorates Achilles tendon microcirculation immediately following suturing.MethodsFifteen Achilles tendons of eight male Wistar rats (275–325 g) were included. After preparation of the Achilles tendon with a medial paratendinous approach, Achilles tendon microcirculation was assessed using combined Laser-Doppler and spectrophotometry (Oxygen-to-see) regarding:- tendinous capillary blood flow [arbitrary units AU]- tendinous tissue oxygen saturation [%]- tendinous venous filling pressure [rAU]The main body of the Achilles tendon was measured in the center of the suture with 50 Hz. 10 minutes after Achilles tendon suture (6-0 Prolene), a second assessment of microcirculatory parameters was performed.ResultsAchilles tendon capillary blood flow decreased by 57% following the suture (70 ± 30 AU vs. 31 ± 16 AU; p < 0.001). Tendinous tissue oxygen saturation remained at the same level before and after suture (78 ± 17% vs. 77 ± 22%; p = 0.904). Tendinous venous filling pressure increased by 33% (54 ± 16 AU vs. 72 ± 20 AU; p = 0.019) after suture.ConclusionAchilles tendon suture in anaesthetised rats causes an acute loss of capillary perfusion and increases postcapillary venous filling pressures indicating venous stasis. The primary hypothesis of this study was confirmed. In contrast, tendinous tissue oxygen saturation remains unchanged excluding acute intratendinous hypoxia within the first 10 minutes after suture. Further changes of oxygen saturation remain unclear. Furthermore, it remains to be determined to what extent reduced capillary blood flow as well as increased postcapillary stasis might influence tendon healing from a microcirculatory point of view in this animal setting.

Severe burn injuries caused by bioethanol-design fireplaces-an overview on recreational fire threats.

Commercially available bioethanol-fueled fireplaces have become increasingly popular additions for interior home decoration in Europe and more recently in the United States. These fireplaces are advertised as smokeless, ecologically friendly, and do not require professional installation, formal gas lines, or venting. Although manufacturers and businesses promote their safety, recent presentations of injuries have alerted the authors to the relevant danger bioethanol fireplaces can pose for the incautious user. Are bioethanol fireplaces going to become the future threat in domestic burn accidents beside common barbeque burns? A Medline literature search on barbeque and domestic fireplace accidents was performed to compare and stratify the injury patterns reported and to identify a risk profile for contemporary bioethanol-fueled fireplaces. To exemplify, two representative clinical cases of severe burn accidents caused by bioethanol-fueled fireplaces, both treated in the burn unit of the authors, are being presented. Design fireplaces are being recognized as an increasing source of fuel and fire-related danger in the home. This risk may be underestimated by the uninformed customer, resulting in severe burn injuries. Because bioethanol-fueled fireplaces have become more commonplace, they may overtake barbecue-related injury as the most common domestic burn injury.

Eccentric Training and an Achilles Wrap Reduce Achilles Tendon Capillary Blood Flow and Capillary Venous Filling Pressures and Increase Tendon Oxygen Saturation in Insertional and Midportion Tendinopathy: A Randomized Trial

Background Eccentric training has been demonstrated to decrease pain in patients with Achilles tendinopathy. Whether an Achilles wrap in addition to eccentric training changes parameters of tendon microcirculation in insertional and midportion tendinopathy is not known. Study Design Randomized clinical trial; Level of evidence, 2. Methods One hundred twelve subjects were recruited. A laser Doppler system assessed capillary blood flow, tissue oxygen saturation, and postcapillary venous filling pressure. Group A performed daily eccentric training for 12 weeks with additional daily Achilles wrap (AirHeel™, 54 tendons of 54 patients), while group B performed the same eccentric training only (64 tendons of 59 patients). Results Ninety-one patients (81%) completed the 12-week training period. Tendon oxygen saturation increased significantly in group A at the insertion (70% ± 11% to 75% ± 7%, P = .001) and distal midportion (68% ± 12% to 73% ± 9%, P = .006); this increase was greater than that in group B (69% ± 11% vs 68% ± 15%, P = .041 vs A). Postcapillary venous filling pressures were significantly reduced in group A at 5 of 8 positions at 2 and 8 mm tendon depths (up to 26%, P = .003), while only in 3 of 8 positions in group B (up to 20%, P = .001). Pain on the visual analog scale was 5.1 ± 2.1 vs 3.2 ± 2.7 (A,–37.3%, P = .0001) and 5.5 ± 2.1 vs 3.6 ± 2.4 (B, P = .0001,–34.6%) (P = .486 for A vs B). Conclusion Tendon oxygen saturation was increased, and capillary venous clearance facilitated using an Achilles wrap in addition to a daily 12-week eccentric training program. Achilles wrap and eccentric training increased subjective assessment of Achilles tendinopathy, while pain level reduction remained the same in both groups.

Diabetes and Peripheral Arterial Occlusive Disease Impair the Cutaneous Tissue Oxygenation in Dorsal Hand Microcirculation of Elderly Adults: Implications for Hand Rejuvenation

BACKGROUND In spite of potential implications for anti‐aging therapy regarding the selection of the most suitable therapeutical method and potential perinterventional complications, cutaneous microcirculation of the aging hand in healthy individuals as well as in those with diabetes mellitus or peripheral arterial occlusive disease (PAOD) has never been evaluated. HYPOTHESIS Functional microcirculation of the dorsal hand differs between healthy individuals and individuals with diabetes or PAOD at the same age. MATERIALS AND METHODS Prospective controlled cohort study. One hundred ten individuals were allocated to group A (healthy individuals, n = 37), group B (diabetes mellitus, n = 36), and group C (PAOD, n = 37). Microcirculatory data were obtained using combined laser‐Doppler and photospectrometry. RESULTS Cutaneous oxygen saturation at the dorsal hand of healthy individuals was 11.1% higher than of those with diabetes mellitus (p = .04) and 18.8% higher than of those with PAOD (p = .001). Cutaneous capillary blood flow in participants with PAOD was 20% higher than in healthy individuals (p = .047). CONCLUSION This is the first study demonstrating that capillary microcirculation of the dorsal hand differs between healthy individuals and those with diabetes or PAOD of the same age. Further studies should explore whether ameliorating cutaneous tissue oxygen saturation could emerge as a viable antiaging strategy for elderly hands.

Microcirculatory effects of acupuncture and hyperthermia on Achilles tendon microcirculation.

Dear editor, We read with great interest the recent report from Kubo et al. focusing on the effects of acupuncture (dry needling) and heating (application of hot pack) on Achilles tendon microcirculation in healthy male subjects (Kubo et al. 2010). We would like to comment on some observations and conclusions made by the authors. Kubo stated that acupuncture and heating treatments could contribute to tendon repair of chronic tendinopathy as the blood volume and oxygen saturation of the human Achilles tendon increased during acupuncture and heating treatments. To the best of our current knowledge, it is at best hypothesized that increased oxygen saturation is beneficial to tendon repair in chronic tendinopathy. Furthermore, an increase in blood volume is in our understanding an increase in postcapillary venous filling pressure in the capillary bed. As such, venous congestion on a microcirculatory level is reflected by an increase of the blood volume. The authors should comment on this interpretation. Furthermore, healthy Achilles tendons might not necessarily react the same as tendinopathic tendons on a given treatment, such as hyperthermia or acupuncture. Based on a hypothesized continuum from the healthy Achilles tendon via the tendinopathic state to the tendon rupture, current scientific data demonstrates neovascularisation and neoneuralisation as pathoanatomic correlates of chronic Achilles tendinopathy (Knobloch et al. 2006). We found that baseline Achilles tendon microcirculation in healthy volunteers is significantly different to insertional as well as mid-portion Achilles tendinopathy, as capillary blood flow is significantly increased at the point of pain (Knobloch et al. 2006). In addition, eccentric training, which is able to relieve pain in randomized-controlled trials (Knobloch et al. 2007), reduces increased capillary blood flow by up to 50% over 12 weeks of training (Knobloch 2007). Cryotherapy with or without additional compression, decreases capillary blood flow and notably increases Achilles tendon oxygen saturation in healthy volunteers (Knobloch et al. 2008). Therefore, the findings achieved by Kubo might be discussed given the aforementioned observations. Current understanding regarding chronic tendinopathy suggests that chronic ischaemic conditions are associated with decreased intratendinous oxygen saturation leading to intratendinous neovascularisation and neoneuralisation. Nevertheless, further studies at best in a randomized-controlled fashion are mandatory to elucidate the intratendinous pathoanatomic behaviour of neovessels in chronic Achilles tendinopathy after a given intervention, such as accupuncture and/or hyperthermia using semiquantitative assessment methods of neovascularization by power Doppler or direct capillary blood flow measurement based or laser Doppler flowmetry. We would like to congratulate the authors for their inspiring work.