Michael W. Maier

Are there differences between stemless and conventional stemmed shoulder prostheses in the treatment of glenohumeral osteoarthritis

BackgroundConventional stemmed anatomical shoulder prostheses are widely used in the treatment of glenohumeral osteoarthritis. The stemless shoulder prosthesis, in contrast, is a new concept, and fewer outcome studies are available. Therefore, the purpose of the study was to investigate the early functional outcome and postoperative proprioception of a stemless prosthesis in comparison with a standard stemmed anatomic shoulder prosthesis.MethodsTwelve patients (mean age 68.3xa0years [SDu2009±u20095.4]; 5 female, 7 male) with primary glenohumeral osteoarthritis of the shoulder were enrolled, who underwent total shoulder arthroplasty (TSA) with a stemless total shoulder prosthesis, Total Evolution Shoulder System (TESS®; Biomed, France). The control group consisted of twelve (age and gender matched) patients (mean age 67.8xa0years; [SDu2009±u20097.1]; 9 female, 3 male), getting a TSA with a standard anatomic stemmed prosthesis, Aequalis® Shoulder (Tournier, Lyon, France). Patients were examined the day before and six months after surgery. The pre- and postoperative Constant Score (CS) was evaluated and proprioception was measured in a 3D video motion analysis study using an active angle-reproduction (AAR) test.ResultsComparing the postoperative CS, there was no significant difference between the groups treated with the TESS® prosthesis (48.0u2009±u200913.8 points) and the Aequalis® prosthesis (49.3u2009±u20098.6 points; pu2009=u20090.792). There was no significant difference in postoperative proprioception between the TESS® group (7.2° [SDu2009±u20092.8]) and the Aequalis® group(8.7° [SDu2009±u20092.7]; pu2009=u20090.196), either. Comparison of in the results of CS and AAR test pre- and postoperatively showed no significant differences between the groups.DiscussionIn patients with glenohumeral osteoarthritis, treated with TSA, the functional and the proprioceptive outcome is comparable between a stemless and a standard stemmed anatomic shoulder prosthesis at early followup.ConclusionFurther follow-up is necessary regarding the long-term performance of this prosthesis.Trial registrationCurrent Controlled Trials DRKS 00007528. Registered 17 November 2014

Primary stability of the Fitmore® stem: biomechanical comparison

PurposeAfter clinical introduction of the Fitmore® stem (Zimmer), we noticed the formation of cortical hypertrophies in a few cases. We questioned whether (1) the primary stability or (2) load transfer of the Fitmore® stem differs from other stems unassociated with the formation of hypertrophies. We compared the Fitmore® stem to the well-established CLS® stem.MethodsFour Fitmore® and four CLS® stems were implanted in eight synthetic femurs. A cyclic torque around the stem axis and a mediolateral cyclic torque were applied. Micromotions between stems and femurs were measured to classify the specific rotational implant stability and to analyse the bending behaviour of the stem.ResultsNo statistical differences were found between the two stem designs with respect to their rotational stability (pu2009=u20090.82). For both stems, a proximal fixation was found. However, for the mediolateral bending behavior, we observed a significantly (pu2009<u20090.01) higher flexibility of the CLS® stem compared to the Fitmore® stem.ConclusionHip stem implantation may induce remodelling of the periprosthetic bone structure. Considering the proximal fixation of both stems, rotational stability of the Fitmore® stem might not be a plausible explanation for clinically observed formation of hypertrophies. However, bending results support our hypothesis that the CLS® stem presumably closely follows the bending of the bone, whereas the shorter Fitmore® stem acts more rigidly. Stem rigidity and flexibility needs to be considered, as they may influence the load transfer at the implant–bone interface and thus possibly affect bone remodelling processes.

Cortical hypertrophy with a short, curved uncemented hip stem does not have any clinical impact during early follow-up

BackgroundShort stems have become more and more popular for cementless total hip arthroplasty in the past few years. While conventional, uncemented straight stems for primary total hip arthroplasty (THA) have shown high survival rates in the long term, it is not known whether uncemented short stems represent a reasonable alternative. As cortical hypertrophy has been reported for short stems, the aim of this study was to determine the radiographic prevalence of cortical hypertrophy and to assess the clinical outcome of a frequently used short, curved hip stem.MethodsWe retrospectively studied the clinical and radiographic results of our first 100 consecutive THAs (97 patients) using the Fitmore® hip stem. Mean age at the time of index arthroplasty was 59xa0years (range, 19 – 79xa0years). Clinical outcome and radiographic results were assessed with a minimum follow-up of 2xa0years, and Kaplan-Meier survivorship analysis was used to estimate survival for different endpoints.ResultsAfter a mean follow-up of 3.3xa0years (range, 2.0 – 4.4xa0years), two patients (two hips) had died, and three patients (four hips) were lost to follow-up. Kaplan-Meier analysis estimated a survival rate of 100xa0% at 3.8xa0years, with revision for any reason as the endpoint. No femoral component showed radiographic signs of loosening. No osteolysis was detected. Cortical hypertrophy was found in 50 hips (63xa0%), predominantly in Gruen zone 3 and 5. In the cortical hypertrophy group, two patients (two hips; 4xa0%) reported some thigh pain in combination with pain over the greater trochanter region during physical exercise (UCLA Score 6 and 7). There was no significant difference concerning the clinical outcome between the cortical hypertrophy and no cortical hypertrophy group.ConclusionsThe survival rate and both clinical and the radiographic outcome confirm the encouraging results for short, curved uncemented stems. Postoperative radiographs frequently displayed cortical hypertrophy but it had no significant effect on the clinical outcome in the early follow-up. Further clinical and radiographic follow-up is necessary to detect possible adverse, long-term, clinical effects of cortical hypertrophy.

The effects of muscle-tendon surgery on dynamic electromyographic patterns and muscle tone in children with cerebral palsy

During multilevel surgery, muscle-tendon lengthening (MTL) is commonly carried out in children with cerebral palsy. However, it is unclear if MTL also modifies increased muscle tone and if pathologic activation patterns are changed as an indirect effect of the biomechanical changes. Since investigations addressing this issue are limited, this study aimed at evaluating the effects of MTL on muscle tone and activation pattern. Forty-two children with spastic diplegia who were treated by MTL underwent standardized muscle tone testing (modified Ashworth and Tardieu test), dynamic EMG and three-dimensional gait analysis before, one and three years after MTL. For the evaluation of muscle activation patterns the norm-distance of dynamic EMG data was analyzed. Range of motion and joint alignment in clinical examination were found to be significantly improved one year after MTL. However, deterioration of these parameters was noted after three years. Muscle tone was significantly reduced one year postoperatively but showed an increase after three years. Joint kinematics were found significantly closer to reference data of age matched controls initially after surgery, but deteriorated until three years postoperatively. However, the EMG patterns of the muscles which were surgically addressed were found to be unchanged in either follow-up. These findings suggest that despite the influence of MTS on biomechanics and physiology (muscle tone reduction and improvements of joint mobility and gait pattern) MTS does not change abnormal patterns of muscle activation. Recurrence of increased muscle tone and deterioration of kinematic parameters three years after surgery may be attributed to these persistent pathologic activation patterns.

Motion patterns in activities of daily living: 3- year longitudinal follow-up after total shoulder arthroplasty using an optical 3D motion analysis system

BackgroundTotal shoulder arthroplasty (TSA) can improve function in osteoarthritic shoulders, but the ability to perform activities of daily living (ADLs) can still remain impaired. Routinely, shoulder surgeons measure range of motion (ROM) using a goniometer. Objective data are limited, however, concerning functional three-dimensional changes in ROM in ADLs after TSA in patients with degenerative glenohumeral osteoarthritis.MethodsThis study included ten consecutive patients, who received TSA for primary glenohumeral osteoarthritis. The patients were examined the day before, 6 months, and 3 years after shoulder replacement as well. We compared them with a control group (n = 10) without any shoulder pathology and measured shoulder movement by 3D motion analysis using a novel 3 D model. The measurement included static maximum values, the ability to perform and the ROM of the ADLs “combing the hair”, “washing the opposite armpit”, “tying an apron”, and “taking a book from a shelf”.ResultsSix months after surgery, almost all TSA patients were able to perform the four ADLs (3 out of 40 tasks could not be performed by the 10 patients); 3 years postoperatively all patients were able to carry out all ADLs (40 out of 40 tasks possible). In performing the ADLs, comparison of the pre- with the 6-month and 3-year postoperative status of the TSA group showed that the subjects did not fully use the available maximum flexion/extension ROM in performing the four ADLs. The ROM used for flexion/extension did not change significantly (preoperatively 135°-0° -34° vs. 3 years postoperatively 131° -0° -53°). For abduction/adduction, ROM improved significantly from 33°-0° -27° preoperatively to 76° -0° -35° postoperatively. Compared to the controls (118°) the TSA group used less ROM for abduction to perform the four ADLs 3 years postoperatively.ConclusionTSA improves the ability to perform ADL and the individual ROM in ADLs in patients with degenerative glenohumeral osteoarthritis over the course of 3xa0years. However, TSA patients do not use their maximum available abduction ROM in performing ADLs. This is not related to limitations in active ROM, but rather may be caused by pathologic motion patterns, impaired proprioception or both.

3D motion capture using the HUX model for monitoring functional changes with arthroplasty in patients with degenerative osteoarthritis.

BACKGROUNDnAlthough shoulder hemiarthroplasty (SHA) can improve function in osteoarthritic shoulders, the ability to perform activities of daily living (ADL) may remain impaired. Shoulder surgeons routinely measure parameters such as range of motion, pain, satisfaction and strength. A common subjective assessment of ADL is part of the Constant Score (CS). However, there is limited objective evidence on whether or not shoulder hemiarthroplasty can restore normal range of motion (ROM) in ADL.nnnMETHODSnThe study included eight consecutive patients (n=8; seven women, one man), who underwent SHA for glenohumeral osteoarthritis. The patients were examined the day before, as well as 6 months and 3 years after shoulder replacement. They were compared with a control group with no shoulder pathology, and shoulder movement was measured with 3D motion analysis using the Heidelberg Upper Extremity (HUX) model. Measurements included static maximum values and four ADL.nnnRESULTSnComparing the preoperative to the 3-year postoperative static maximum values, there were significant improvements for abduction from 50.5° (SD ± 3 2.4°) to 72.4° (SD ± 38.2°; p=0.031), for adduction from 6.2° (SD ± 7.7°) to 66.7° (SD ± 18.0°; p=0.008), for external rotation from 15.1° (SD ± 27.9°) to 50.9° (SD ± 27.3°; p=0.031), and for internal rotation from -0.6° (SD ± 3.9°) to 35.8° (SD ± 28.2°; p=0.031). There was a trend of improvement for flexion from 105.8° (SD ± 45.7°) to 161.9° (SD ± 78.2°; p=0.094) and for extension from 20.6° (SD ± 17.0°) to 28.0° (SD ± 12.5°; p=0.313). The comparison of the 3-year postoperative ROM between the SHA group and controls showed significant differences in abduction; 3-year postoperative SHA ROM 72.4° (SD ± 38.2°) vs. 113.5° (SD ± 29.7°) among controls (p=0.029). There were no significant differences compared to the control group in adduction, flexion/extension and rotation 3 years after SHA surgery. In performing the ADL, the pre- to the 6-month and 3-year postoperative status of the SHA group resulted in a significant increase in ROM in all planes (p<0.05). Comparing the preoperative to the 3-year postoperative ROM used in ADL, there was an improvement in the flexion/extension plane, showing an improvement trend from preoperative 85°-0°-25° to postoperative 127°-0°-38° (p=0.063). In comparison, controls used a significantly greater ROM during ADL with mean flexion/extension of 139°-0°-63° (p=0.028). For the abduction/adduction plane, ROM improved significantly from preoperative 25°-0°-19° to postoperative 78°-0°-60° (p=0.031). In comparison to controls with abduction/adduction of 118°-0°-37° 3 years postoperative, the SHA group also used significantly less ROM in the abduction/adduction plane (p=0.028).nnnCONCLUSIONnWhile SHA improves ROM in ADL in patients with degenerative glenohumeral osteoarthritis, it does not restore the full ROM available for performing ADL compared to controls. 3D motion analysis with the HUX model is an appropriate measurement system to detect surgery-related changes in shoulder arthroplasty.

Does additional patella tendon shortening influence the effects of multilevel surgery to correct flexed knee gait in cerebral palsy: A randomized controlled trial

BACKGROUNDnThe aims of this study were to investigate if patellar tendon shortening (PTS) as a part of SEMLS (single event multilevel surgery) is effective for reduction of flexed knee gait in children with cerebral palsy (CP) and, if PTS leads to stiff knee gait.nnnMETHODSnIn a randomized controlled study 22 children with flexed knee gait (age: 10.4u202f±u202f2.6u202fyears, GMFCS Level I-III) were randomized and allocated to two groups (1: SEMLSu202f+u202fPTS; 2: SEMLS no PTS): SEMLS was performed for correction of flexed knee gait either with or without additional PTS. Before and after surgery (follow up: 12.7u202f±u202f1.6u202fmonths) kinematics (3-D motion analysis) and clinical parameters were compared.nnnRESULTSnTwo children were lost to follow up. Maximum knee extension improved significantly in both groups after SEMLS while the patients with additional PTS showed much more correction (SEMLSu202f+u202fPTS: 37.6° to 11.4°, pu202f=u202f0.007; SEMLS no PTS: 35.1° to 21.8°, pu202f=u202f0.016). After surgery peak knee flexion decreased significantly (14.6°, pu202f=u202f0.004) in the SEMLSu202f+u202fPTS group while there was no relevant change in the other group. There was a trend of increase in anterior pelvic tilt after surgery in both groups, but no statistical significant difference. After surgery knee flexion contracture (15.9°, pu202f<u202f0.001) and popliteal angle (27.2, pu202f=u202f0.009) measured on clinical examination only decreased significantly in the SEMLSu202f+u202fPTS group.nnnCONCLUSIONnPTS is effective for correction of flexed knee gait and knee flexion contracture leading to superior stance phase knee extension. However, additional PTS may lead to stiff knee gait and a higher increase of anterior pelvic tilt.

How does reverse shoulder replacement change proprioception in patients with cuff tear arthropathy? A prospective optical 3D motion analysis study

BACKGROUNDnReverse total shoulder arthroplasty (RSA) can improve function in cuff tear arthropathy (CTA) shoulders, but limited data are available on the effect of RSA on proprioception. The purpose of this study was the evaluation of the proprioception after RSA.nnnMETHODnThis study included fifteen consecutive patients (nxa0=xa015) who received an RSA. We measured an active angle reproduction (AAR) by a novel 3D motion analysis using the Heidelberg upper extremity model (HUX).nnnRESULTSnThe overall proprioception didnt change significantly from 6.2° preoperatively to 6.2° postoperatively.nnnCONCLUSIONnWe conclude that, the overall proprioception remained the same or deteriorated for different movements.

The influence of timing of knee recurvatum on surgical outcome in cerebral palsy

Recent reports have shown that timing of genu recurvatum (GR) might be caused by different underlying factors and that equinus leads to GR especially during early stance. The purpose of this study was to investigate the reduction of GR after surgical correction of equinus in children with bilateral spastic cerebral palsy and whether the children with early and late type GR show differences in reduction of knee hyperextension after a surgery. In 24 limbs (mean age 10.3 years, GMFCS I-III) showing equinus and GR the kinematics of the knee and ankle as well as the kinetics of the knee were evaluated before and one year (mean follow up period: 12.8 months) after surgical correction of equinus. The study was approved by the local ethical committee. Limbs with early type GR showed a reduction by 11.1° (p<0.001) and those with late type GR by 6.0° (p<0.049) in GR after surgery. Before surgery limbs with early type GR showed increased external extending moments, which decreased significantly after surgery. In contrast limbs with late GR did not show a significant reduction of those moments. The findings of this study underline the influence of equinus on early GR as an underlying factor. As equinus is attributed to early knee hyperextension and proximal factors are more important as underlying factors in late type GR, a classification into early and late onset GR is useful to identify underlying factors and to choose adequate treatment.

Can reverse shoulder arthroplasty in post-traumatic revision surgery restore the ability to perform activities of daily living?

BACKGROUNDnFailed shoulder arthroplasty and failed internal fixation in fractures of the proximal humerus can benefit from implantation of a reverse total shoulder arthroplasty (RSA). While there is some evidence that RSA can improve function regarding range of motion (ROM), pain, satisfaction, and strength, there is sparse data how this translates into activities of daily living (ADLs). A marker-based 3D video motion analysis system has recently been designed that can measure changes of ROM in dynamic movements in every plane. The hypothesis was that a gain of maximum ROM also translates into the ability to perform ADLs and into a significant increase of ROM in ADLs.nnnMATERIALS AND METHODSnSix consecutive patients (5 women, 1 man; 2× failed arthroplasty, 4× failed open reduction and internal fixation) who received RSA were examined the day before and 1 year after shoulder replacement. A 3D motion analysis system using a novel upper extremity model measured active maximum values and ROM in four ADLs.nnnRESULTSnComparing the pre- to the 1-year postoperative status, RSA resulted in a significant increase in mean maximum values for active flexion (humerus to thorax) of 37° (S.D. ±23°), from 50 to 87° [P=0.005], and for active abduction averaging of 17° (S.D. ±13°), from 52 to 69° [P=0.027]. The extension decreased significantly by about 8° (S.D. ±16°), from a mean of 39 to 31° [P=0.009]. For active adduction and internal and external rotation, there were trends for improvements, but no significant changes. Only three additional tasks of the ADL (out of 13/24 preoperatively) could be performed after revision surgery. Comparing the preoperative to the postoperative ROM in the ADLs in flexion/extension, ROM improved significantly in one (tying an apron) of four ADLs. There were no significant changes in the abduction/adduction and internal/external rotation in any ADLs.nnnCONCLUSIONnRSA in revision cases significantly improved maximum active flexion and abduction, but decreased extension in this series. However, the patients were only able to use this greater ROM to their benefit in one of four ADLs.