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Dive into the research topics where Leif Claassen is active.

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Featured researches published by Leif Claassen.


Technology and Health Care | 2014

Range of motion assessment of the shoulder and elbow joints using a motion sensing input device: a pilot study.

Nael Hawi; Emmanouil Liodakis; Daut Musolli; Eduardo M. Suero; Timo Stuebig; Leif Claassen; Carsten Kleiner; Christian Krettek; Volker Ahlers; Musa Citak

BACKGROUND Motion sensing input devices could provide a practical and low-cost alternative method for repeated range of motion measurements. This study aimed to assess the reliability, accuracy and time requirements of a motion sensing input device (Microsoft Kinect) for ROM measurements comparing it with goniometer based measurements and subjective estimation. MATERIAL AND METHODS Full ROM was measured in 14 shoulder and elbow joints using the different methods. The order was randomly selected and each movement was measured twice. The results were recorded in degrees and the time measured in seconds. RESULTS In general, there was a poor to moderate agreement between the Kinect system compared to the goniometer. There was a good agreement between the goniometer-based and the subjective technique. The Kinect-based technique showed excellent test-retest reliability. CONCLUSION The Kinect system showed good test-retest reliability, but lower accuracy compared to goniometer-based measurements. Improvements in patient positioning and measurement protocol standardization must be made before its implementation in clinical practice.


Journal of Orthopaedic Research | 2016

Early results using a biodegradable magnesium screw for modified chevron osteotomies: MG SHORT TERM

Christian Plaass; Sarah Ettinger; Lena Sonnow; Soeren Koenneker; Yvonne Noll; Andreas Weizbauer; Janin Reifenrath; Leif Claassen; Kiriakos Daniilidis; Christina Stukenborg-Colsman; Henning Windhagen

This is the first larger study analyzing the use of magnesium‐based screws for fixation of modified Chevron osteotomies in hallux valgus surgery. Forty‐four patients (45 feet) were included in this prospective study. A modified Chevron osteotomy was performed on every patient and a magnesium screw used for fixation. The mean clinical follow up was 21.4 weeks. The mean age of the patients was 45.5 years. Forty patients could be provided with the implant, in four patients the surgeon decided to change to a standard metallic implant. The AOFAS, FAAM and pain NRS‐scale improved markedly. The hallux valgus angle, intermetatarsal angle and sesamoid position improved significantly. Seven patients showed dorsal subluxation, rotation or medial shifting of the metatarsal heads within the first 3 months. One of these patients was revised, in all others the findings were considered clinically not significant or the patients refused revision. This study shows the feasibility of using magnesium screws in hallux valgus‐surgery. Surgeons starting with the use of these implants should be aware of the proper handling of these implants and should know about corrosion effects during healing and its radiographic appearance.


Foot & Ankle International | 2016

Operative Treatment of the Insertional Achilles Tendinopathy Through a Transtendinous Approach.

Sarah Ettinger; Rameez Razzaq; Hazibullah Waizy; Leif Claassen; Kiriakos Daniilidis; Christina Stukenborg-Colsman; Christian Plaass

Background: Different operative techniques have been proposed for the treatment of insertional Achilles tendinopathy (IAT), with often disappointing results. The aim of this study was to evaluate the outcome of the transtendinous approach in IAT. Methods: Forty patients operated with an IAT between 2010 and 2011 were included in this retrospective study. The mean follow-up was 15.6 (±3.7, 12-27) months. Indication for surgery was IAT with failed conservative therapy. Using a transtendinous approach, the Achilles tendon (AT) was partially detached and all pathologic tissues were debrided. The AT was reinserted using different anchor techniques. Clinical data were recorded using examination and clinical scores (American Orthopaedic Foot & Ankle Society [AOFAS], Foot and Ankle Outcome Score [FAOS], Numerical Rating Scale [NRS], and Short Form-36 [SF-36]). Results: The mean AOFAS hindfoot score improved from 59.4 preoperatively to 86.5 postoperatively (P < .05). All FAOS subscales, NRS pain scores, and pain and function subscales of SF-36 improved significantly. The median time of return to work and sports was 14.5 (±17.6; 2-82) and 22.7 (±13.4; 7-58) weeks. Three patients had superficial wound healing difficulties but required no revision. One patient had to be revised due to a hematoma. Patients treated with 2 suture anchors or double-row fixation technique improved significantly (P < .05) compared to those with single anchor fixation, regarding AOFAS score (79.6 and 90.2) and FAOS subscale scores. Eighty-three percent of the patients showed good to excellent results. Conclusion: The transtendinous approach allowed access to all associated pathologies in IAT. It had relatively few complications and lead to good clinical results. Level of Clinical Evidence: Level IV, retrospective case series.


Foot & Ankle International | 2016

Placement of Plantar Plates for Lapidus Arthrodesis Anatomical Considerations

Christian Plaass; Leif Claassen; Kiriakos Daniilidis; Mariesol Fumy; Christina Stukenborg-Colsman; Andreas Schmiedl; Sarah Ettinger

Background: The modified Lapidus procedure is an accepted treatment option for patients with moderate to severe hallux valgus. Placing a plate plantar on the tension side of the arthrodesis has been shown to be biomechanically superior and has provided good clinical results. There is some concern about interference of the plantar placed plates on the tendon insertions. The purpose of this study was to determine a “safe zone” for plantar plate placement without irritation of the tendons. Methods: Twenty-nine embalmed right feet were used for this study. The anatomy of the insertion of the peroneus longus (PL) tendon and tibialis anterior (TA) tendon on the medial cuneiform and first metatarsal were analyzed. Six different plate designs for plantar plating of the first tarsometatarsal fusion were included. The fit to the bone and contact to tendon insertion were analyzed. Results: The PL showed a main insertion to the first metatarsal and a lesser insertion to the medial cuneiform. The TA inserted onto the medial cuneiform and first metatarsal in all cases in our series. There was a “safe zone” between the TA and PL insertion areas for plate placement. Straight, Y- and U-shaped plates could be placed without compromising the tendon insertion. Depending on the design, even preshaped plates may have to be bent to allow a good fit to the plantar side of the first tarsometatarsal joint. Conclusion: Plantar plating for modified Lapidus arthrodesis can be safely performed, without damaging the plantar tendon insertion area of the PL and TA. Clinical Relevance: The exact knowledge of the anatomy of the plantar region of the tarsometatarsal joint can help to improve plate placement.


Foot & Ankle International | 2014

Role of MRI in Detection of Morton’s Neuroma

Leif Claassen; Kilian Bock; Max Ettinger; Hazibullah Waizy; Christina Stukenborg-Colsman; Christian Plaass

Background: Distinguishing between patients with a true Morton’s neuroma and other forefoot pathology can be difficult. The aim of this study was to evaluate the diagnostic accuracy of routine magnetic resonance imaging (MRI) when compared to clinical examination for Morton’s neuroma. Methods: We retrospectively identified 71 patients who underwent operative treatment due to the diagnosis of Morton’s neuroma between 2007 and 2013. All patients had a MRI preoperative. Our study group comprised 58 female and 13 male patients with a mean age of 57 (range, 38-92) years. We compared the results of preoperative MRI and the patient’s clinical assessment with postoperative histopathological results. Results: Typical clinical signs were found in 65 cases. Most common symptoms were plantar pain (92%) and increased pain on walking (89%). A Morton’s neuroma was detected on MRI in 59 of 71 cases. Its sensitivity was 0.84 and its specificity was 0.33. The positive and negative predictive values were 0.97 and 0.08, respectively. For the presence of main clinical symptoms we found a sensitivity of 0.94 and a specificity of 0.33. The positive predictive value was 0.97 and the negative predictive value was 0.20. Conclusion: MRI under routine conditions had a good detection rate for the evaluation of Morton’s neuroma. However, its accuracy was not as high as the accuracy of clinical assessment. Level of Evidence: Level IV, retrospective series.


Orthopedic Reviews | 2014

Preoperative diagnostic for periprosthetic joint infection prior to total knee revision arthroplasty

Leif Claassen; Kerstin Radtke; Max Ettinger; Christian Plaass; Gabriela von Lewinski

Periprosthetic joint infection (PJI) after total knee arthroplasty remains a challenging problem. The aim of this study was to evaluate the accuracy of diagnostic knee aspiration and serum inflammatory markers in diagnostic of a PJI after total knee arthroplasty. Within 2011 and 2012, 46 patients received a one- or two-stage revision arthroplasty of the knee joint. These patients received a total number of 77 operations. A preoperative aspiration was performed in each case. We analyzed the microbiological and histological examinations of the samples from the aspiration and from the revision operation and additionally estimated serum inflammatory markers. The diagnostic aspiration had a specificity of 0.87, a sensitivity of 0.39, a positive predictive value of 0.67 and a negative predictive value of 0.68. For C-reactive protein the specificity was 0.61 and the sensitivity was 0.48, the serum white blood cell count had a specificity of 0.98 and a sensitivity of 0.23. Our data queries whether diagnostic joint aspiration or serum inflammatory markers are sufficient to verify or exclude a PJI.


Journal of Foot & Ankle Surgery | 2016

Surgical Management of Charcot Deformity for the Foot and Ankle—Radiologic Outcome After Internal/External Fixation

Sarah Ettinger; Christian Plaass; Leif Claassen; Christina Stukenborg-Colsman; Daiwei Yao; Kiriakos Daniilidis

Charcot neuropathy (CN) is a severe joint disease that makes surgical planning very challenging, because it is combined with ankle instability, serious deformities, and recurrent ulceration. The aim of the present study was to examine the rate of bone fusion after external or internal fixation in patients with CN. We retrospectively examined 58 patients with CN who had undergone reconstruction of the ankle either with tibiotalocalcaneal or tibiocalcaneal arthrodesis. The mean age was 59.1 (range 26 to 81) years at surgery. Of the 58 patients, 38 were treated using intramedullary nail arthrodesis and 19 using an external fixator (1 patient received neither). At a mean follow-up period of 31.3 (range 12 to 57) months, limb salvage and bone fusion had been achieved in 94.83%. The mean time to bone fusion was 12 (range 6 to 18) months. Three patients (5.2%) required a more proximal amputation. All but these 3 patients gained independent mobilization in custom feet orthoses or off the shelf orthoses. Of the 58 patients in the present cohort, 56 (96.6%) would undergo surgery again. In conclusion, internal and external fixation both lead to promising results in the treatment of CN. Internal fixation should be preferred when no indications of ulcer or infection are present.


Journal of Foot & Ankle Surgery | 2017

Results of HemiCAP® Implantation as a Salvage Procedure for Osteochondral Lesions of the Talus

Sarah Ettinger; Christina Stukenborg-Colsman; Hazibullah Waizy; Christoph Becher; Daiwei Yao; Leif Claassen; Yvonne Noll; Christian Plaass

ABSTRACT Osteochondral defects (OCDs) of the talus remain a surgical challenge, especially after failed primary treatment. The aim of the present study was to examine the clinical outcomes after HemiCAP® implantation for OCDs of the medial talar dome after failed previous surgery. Our retrospective study included 11 patients, who had undergone surgery from June 2009 to September 2012 for an OCD of the medial talar dome and received a HemiCAP® on the talus after failed previous surgery for OCD. The data were acquired using patients’ medical records and standardized questionnaires, including the Foot and Ankle Outcome Score (FAOS), University of California at Los Angeles (UCLA) activity score, EQ‐5D, numerical rating scale (NRS), and Short‐Form 36‐item Health Survey (SF‐36). Using these scores, the possibility of returning to work and sports was determined. Any complications and the need for revision surgery were recorded. One patient refused to participate in the study, leaving 10 patients for evaluation. The mean age was 47.64 ± 10.97 years. The mean follow‐up period was 43.5 ± 35.51 months. The FAOS and SF‐36 subscale scores and the EQ‐5D and UCLA activity scores did not improve significantly (p < .05). The mean postoperative pain score on the NRS improved significantly from 6.6 ± 1.77 preoperatively to 5.1 ± 2.02 postoperatively (p < .05). A greater body mass index led to worse postoperative outcomes with higher scores on the pain‐NRS and less satisfaction (p < .05). Ten revisions for ongoing pain were performed in 7 patients (70.0%) within a mean of 28.4 ± 13.35 months of the initial procedure, and 6 patients (60%) indicated they would undergo surgery again. The results of the present study have shown that implantation of the HemiCAP® as a salvage procedure for OCDs of the talus is challenging and does not consistently lead to good clinical results. Also, overweight patients appear to have an increased risk of postoperative dissatisfaction and persistent ankle pain. &NA; Level of Clinical Evidence: 4


Technology and Health Care | 2013

Computer-assisted navigation of a complex femoral shaft fracture: Instruction in three steps A technical note

Leif Claassen; Nael Hawi; Max Ettinger; Stukenborg-Colsman Ch; Emmanouil Liodakis; Mustafa Citak

The procedure of computer-assisted navigation of femoral shaft fractures is well described. Nevertheless, its use is less common. An unclear disposal and longer operation times might be two reasons. The aim of this technical note is to render assistance concerning the ideal disposal of the setup.


Foot and Ankle Surgery | 2018

The geometrical axis of the talocrural joint—Suggestions for a new measurement of the talocrural joint axis

Leif Claassen; Philipp Luedtke; Daiwei Yao; Sarah Ettinger; Kiriakos Daniilidis; Andrej M. Nowakowski; Magdalena Mueller-Gerbl; Christina Stukenborg-Colsman; Christian Plaass

BACKGROUND Despite intensive research there is no consensus about the talocrural joint axis. The aim of the present study is a new method to determinate the geometric rotational axis of the talocrural joint. METHODS We analyzed 98 CT-scans of full cadaver Caucasian legs. We generated three-dimensional reconstruction models of the talus. A best fitting cone was orientated to the talar articular surface. The geometric rotational axis was defined to be the axis of this cone. RESULTS The geometric rotational axis of the talocrural joint is orientated from lateral-distal to medial-proximal (85.6°±10 compared to anatomical tibial axis in torsional plane), from posterior-distal to anterior-proximal (81.43°±44.35 compared to anatomical tibial axis in sagittal plane) and from posterior-medial to anterior-lateral (169.2°±5.91 compared to intermalleolar axis in axial plane). CONCLUSIONS The consideration of our results might be helpful for better understanding of ankle biomechanics.

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Daiwei Yao

Hannover Medical School

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Max Ettinger

Hannover Medical School

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