The treatment of osteochondral lesions is of great interest to orthopaedic surgeons because most lesions do not heal spontaneously. We present the short-term clinical outcome and MRI findings of a cell-free scaffold used for the treatment of these lesions in the knee. A total of 38 patients were prospectively evaluated clinically for two years following treatment with an osteochondral nanostructured biomimetic scaffold. There were 23 men and 15 women; the mean age of the patients was 30.5 years (15 to 64). Clinical outcome was assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Tegner activity scale and a Visual Analgue scale for pain. MRI data were analysed based on the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) scoring system at three, 12 and 24 months post-operatively. There was a continuous significant clinical improvement after surgery. In two patients, the scaffold treatment failed (5.3%) There was a statistically significant improvement in the MOCART precentage scores. The repair tissue filled most of the defect sufficiently. We found subchondral laminar changes in all patients. Intralesional osteophytes were found in two patients (5.3%). We conclude that this one-step scaffold-based technique can be used for osteochondral repair. The surgical technique is straightforward, and the clinical results are promising. The MRI aspects of the repair tissue continue to evolve during the first two years after surgery. However, the subchondral laminar and bone changes are a concern.

Cite this article: Bone Joint J 2015; 97-B:318–23.

Purpose

to evaluate the radial displacement of meniscal allograft transplants (MATs) in patients operated with an open technique vs. an arthroscopic technique at 1 year postoperatively. Radial displacement or extrusion of the graft is frequently observed after meniscus transplantation. The hypothesis is that arthroscopically inserted MATs extrude less than open MATs and therefore have a more intra-articular position than open surgery transplants.

Background

There is growing evidence in literature that meniscal allograft transplantation performed with the right indications results in significant pain relief and functional improvement of the involved joint. Long-term data on clinical and radiological outcome are however scarce.

Aim

The present study was designed to evaluate the implantation of alginate beads containing human mature allogenic chondrocytes for the treatment of symptomatic cartilage defects in the knee.

Purpose

to evaluate the kinematics of a knee with a polyurethane meniscal scaffold for partial meniscus defect substitution during flexion under weightbearing conditions in an upright MRI. In addition, radial displacement and the surface of the scaffold was compared to the normal meniscus.

Purposes of the study

To assess the performance of an acellular synthetic scaffold in the treatment of painful partial meniscal tissue loss.

Introduction

Autologous chondrocyte implantation presents a viable alternative to microfracture in the repair of damaged articular cartilage of the knee; however, outcomes for patellar lesions have been less encouraging. ChondroCelect (CC) is an innovative, advanced cell therapy product consisting of autologous cartilage cells expanded ex vivo through a highly controlled and consistent manufacturing process.

Femoral fracture non-unions are considered to be rare, and are usually treated successfully with exchange nailing. However, recalcitrant aseptic cases often require additional bone grafting. The efficacy of BMP-7 in the treatment of recalcitrant aseptic femoral non-unions was studied.

Since 2003 a multicenter registry (bmpusergroup.co.uk) was created collecting details of BMP7 application in general, between different university hospitals across Europe. Demographic data, intraoperative details, complications, clinical outcome parameters, radiological healing, VAS pain score, EuroQol-5D, and return-to-work were prospectively recorded. Radiological healing was defined as the presence of callous in two planes over 3 cortices. The minimum follow up was 12 months.

Seventeen patients, who had undergone a median of 1(1 to 4) prior revision operations, over a median period from the injury of 17 months(9 to 42), were included in this observational study. In 76.4%(13/17) the BMP7 was combined with revision of the fixation. Non-union healing was verified in 14/17 cases(82.3%) in a median period of 6.5 months(3–15). Over 80% of these patients returned to their pre-injury level of activities, the median overall health state score was 82.5(35 to 100). No adverse events or complications were associated with the BMP7 application over the median follow-up of 24 months(12–68).

Purpose: Femoral fracture non-unions are considered to be rare, and are usually treated successfully with exchange nailing. However, recalcitrant aseptic cases often require additional bone grafting procedures. The purpose of this study was to investigate the efficacy of BMP-7 (biological enhancement) in the treatment of recalcitrant aseptic femoral non-unions.

Material & Methods: Since 2003 a multicenter registry (bmpusergroup.co.uk) was created to collect details of BMP7 application in general, between different university hospitals across Europe. Demographic data, intraoperative details, complications, clinical outcome parameters, radiological healing, VAS pain score, EuroQol-5D, and return-to-work were prospectively recorded. Radiological healing was defined as the presence of callous in two planes over 3 cortices. The minimum follow up was 12 months.

Results: Thirty patients, who had undergone a median of 1 (1 to 5) prior revision operations, over a median period from the injury of 24 months (9 to 65), were included in this observational study. In 76.7% (23/30) the application of BMP7 was combined with a revision of the fixation. Non-union was verified in 26/30 cases (86.7%) in a median period of 6 months (range 4–10). Over 70% of these patients returned to their preinjury level of activities, the median overall health state score was 82.5 (45 to 95). No adverse events or complications were associated with the BMP7 application over the median follow-up of 30 months (12–68).

Discussion/Conclusion: This case series has verified the safety and efficacy of the use of BMP7 in a manner comparable to the scarce existing evidence on femoral non-unions. The establishment of multicenter networks and the systematic and long-term follow-up of these patients are expected to provide further information and significantly improve our understanding on this promising osteoinductive bone substitute.

Introduction: Post meniscectomy syndrom is an unfavorable disabling outcome for too many patients. This has led to intensive research into finding Methods: for treating irreparable meniscal lesions. The Actifit™ device is a biodegradable, porous, synthetic scaffold for treatment of irreparable partial meniscal tissue loss. When connected to the vascularized zone of the meniscus it promotes blood vessel ingrowth and new tissue generation.

Materials and Methods: Patients with irreparable partial meniscus loss into the vascular zone, intact rim, stable knee or joint stabilization within 3 months post surgery, ICRS classification £ 2, and £ 3 previous surgeries on index knee, and no significant malalignment were treated with the device in a non-randomised, single-arm, multi-centre study. Safety was assessed by frequency of serious adverse device effects (SADEs) and implantation-related serious adverse events (SAEs). Efficacy was assessed based on pain (Visual Analogue Scale [VAS] score) and function (Knee and Osteoarthritis Outcome Score [KOOS] and International Knee Documentation Committee [IKDC] score, and Lysholm Knee Scoring scale) at 3, 6 and 12 months post-operatively. Tissue ingrowth was assessed by dynamic contrast enhanced magnetic resonance imaging (DCMRI) at 3 months, and relook arthroscopy with tissue biopsy at 12 months post-implantation.

Results: 52 subjects (50 with previous meniscectomies) were enrolled. Mean age was 32.9 ±9.0, 77% were male, all stable knees (3 concomitant ACL repairs) mean defect length was 47.8 ± 10.0 mm. A significant mean improvement in knee pain on VAS and function on IKDC and Lysholm scores as well as differnent categories on KOOS were recorded at all follow-ups post-implantation. Tissue ingrowth into the device was observed on DCMRI in 37/43 (86.0%) subjects at 3 months post-implantation. Gross examination at 12 month relook arthroscopy of 45 subjects to date showed no signs of reactions to the device or its degradation products and biopsy samples from the inner free edge of the scaffold meniscus showed fully vital material, with no signs of inflammation. Similar to native meniscal tissue, three distinct layers were observed based on cellular morphology, the presence or absence of vessel structures, and ECM composition.

Conclusion: DCMRI and relook arthroscopy findings illustrate biocompatibility. Tissue ingrowth and biopsy results show potential for differentiation into meniscus-like tissue. Importantly subjects experienced significant pain relief and were able to resume normal activities. No safety concerns have been raised.

On behalf of the Actifit Study Group: R Verdonk, P Beaufils, J Bellemans, P Colombet, R Cugat, P Djian, H Laprell, P Neyret, H Paessler.

Introduction: Partial meniscectomy is the preferred treatment option for patients with irreparable meniscal tears. While generally accepted as producing favorable clinical results in the short run, it is widely accepted that meniscectomy induces articular cartilage degeneration in the long run. Thus, tissue regeneration post-meniscectomy is a desirable therapeutic approach in order to restore the function of the meniscus, thereby preventing long-term damage. A novel device, designed to act as a scaffold for blood vessel ingrowth and meniscal tissue regeneration in patients with irreparable meniscus tears and meniscal tissue loss, has recently been developed.

Methods: Fifty-two patients with an irreparable medial or lateral meniscal tear or partial meniscus loss, with intact rim, were treated with the meniscal scaffold in this prospective, non-randomised, single-arm, multi-centre clinical study. To date, biopsy samples 12 months post-implantation harvested from the center of the inner rim of the implanted scaffold meniscus using a standardized biopsy harvest protocol are available from 9 of the 52 patients. Histochemical staining was performed with haematoxylin and eosin, Masson’s trichrome, Sirius Red and combined Periodic Acid Schiff-Alcian Blue (PAS-AB). Immunohistochemistry was performed using the cartilage markers S100, the vessel markers CD31 and CD34, the smooth muscle marker SMA, and the histiocytic marker CD68.

Results: All biopsies showed fully vital material, with no signs of necrosis or cell death. In addition to a fibrous capsule, 3 distinct zones were identified based on the presence or absence of vessel structures, cellular morphology, and composition of extracellular matrix. Zone 1, a vascularized, fibrotic zone, mainly consisting of fibroblasts, was observed in 4/9 biopsies. Zone 2, an avascular and loose collagenized zone, consisting of a mixture of fibroblasts and chondrofibroblast-like cells, and Zone 3, an avascular and fibrin-rich zone, consisting of fibrochondroblast-like cells, were evident in all 9 biopsies.

Conclusions: All biopsies showed complete re-population, and thus can be regarded as vital structures, illustrating the biocompatibility of the meniscal scaffold. Moreover, zonal organisation, each with its own histological characteristics, suggests an ongoing process of regeneration, maturation and integration towards meniscus-like tissue. These data offer a first insight into the complex human healing potential after implantation of a polyurethane meniscus scaffold.

On behalf of the Actifit Study Group: R Verdonk, P Beaufils, J Bellemans, P Colombet, R Cugat, P Djian, H Laprell, P Neyret, H Paessler,

Introduction: Partial and total meniscectomy has been shown to result in cartilage degeneration and osteoarthritis in the long term. Thus, research efforts have focused on tissue regeneration following meniscectomy. A novel device has recently been developed which, when implanted in the meniscus, provides a three-dimensional honeycombed matrix for vascular ingrowth and tissue regeneration to replace lost meniscus tissue. To evaluate this vascular ingrowth and tissue regeneration a Dynamic contrast-enhanced MRI non invasive technique was used.

Methods: A prospective, non-randomised, single-arm, multi-centre, clinical investigation was conducted in 52 patients with an irreparable medial or lateral meniscal tear or partial meniscus loss, with intact rim. Patients were required to have a stable knee joint or be a candidate for knee joint stabilization within 12 weeks of the index procedure, have an International Cartilage Repair Society (ICRS) classification of Grade I or II, and have undergone no more than 3 previous surgeries on the index knee. Following implantation of the novel scaffold, dynamic contrast-enhanced magnetic resonance imaging (DCMRI) using intravenous gadolinium contrast material was performed at 1 week, and at 3 and 12 months post-implantation. Because the scaffold and normal meniscus tissue lack vascularity, the presence of signal enhancement in the device is an appropriate surrogate for the ingrowth of blood vessels and native tissue into the scaffold. All scans were assessed for neovascularization in the scaffold meniscus and integration of the implanted device. To date DCMRI scans at 3 months are available for 48 of the 52 patients. Full data for all available patients will be presented.

Results: Using this non-invasive technique evaluable DCMRI data at 3 months were obtained for 42 of the 48 patients (87.5%), showing vascularity, and therefore the presence of tissue, in 35 of the 48 (72.9%) patients. No enhancement (vascularity) was demonstrated in 6 of the 48 (12.5%) patients.

Conclusions: At 3 months post-implantation, vascularization, and therefore tissue ingrowth, was demonstrated using DCMRI in the vast majority of patients treated with the novel meniscus scaffold.

Background: There are several surgical options for recurrent lateral dislocations of the patella. As the reconstruction of the medial patellofemoral ligament reconstruction (MPFL) has been proven to restore stability, it has become more accepted by surgeons. No study to date has examined the difference in clinical outcome between patients with a primary MPFL reconstruction (group 1) versus MPFL reconstruction in patients with a previously failed patellar stabilizing operations (transposition of tibial tuberosity, trochleoplasty, medial raphy) (group 2).

Study type: Prospective cohort study

Methods: 30 patients have been treated with an MPFL reconstruction for episodic patellar dislocation between april 2007 and april 2008. 12 of them already had a patellar stabilizing operation in the history (group 2). The clinical follow up was done by the KOOS and KUJULA scores.

Results: For both groups, the KOOS and KUJALA score increased significantly at final follow-up. KOOS pain and ADL subscore had the lowest increase. At final follow-up, the KUJALA and KOOS score were significantly higher for group 1 vs group 2. The net gain for both KOOS and KUJALA was also significantly higher in group 1 compared to group 2.

Conclusions: MPFL reconstruction is a viable treatment option for episodic patellar dislocation both in a primary setting as well as in a secondary setting for failed surgery cases. The net clinical gain is nevertheless significantly higher in primary cases.

Introduction: Currently, partial meniscectomy represents the only viable treatment option for patients with irreparable meniscal tears; however, functional limitations have been reported both in the short- and long-term. Furthermore, over time, removal of knee meniscus tissue leads to degenerative joint changes and osteoarthritis. Given the limited alternatives to meniscus removal, researchers have developed a novel meniscal scaffold. Upon implantation to the vascularized portion of the meniscus, the scaffold allows the ingrowth of blood vessels, facilitating the regeneration of meniscal tissue.

Methods: A total of 52 patients with an irreparable medial or lateral meniscal tear or partial meniscus loss (with intact rim) were recruited into this prospective, non-randomised, single-arm, multi-centre clinical study. Patients were to have a stable knee joint or be a candidate for joint stabilization within 12 weeks of the procedure, an International Cartilage Repair Society (ICRS) classification ≤ 2, and no more than 3 prior surgeries on the index knee. Post-implantation, clinical efficacy was assessed at each follow-up visit based on the following patient-reported outcome scores: Visual Analogue Scale (VAS) score for pain, and both the Knee and Osteoarthritis Outcome Score (KOOS) and International Knee Documentation Committee (IKDC) score for function. Preliminary efficacy data are available for 48/52 patients at 3 months follow-up and 35/52 patients at 6 months follow-up. Full data, including 12 months follow-up for all available patients will be presented.

Results: Compared to the mean baseline values, a statistically significant reduction in post-operative knee pain was reported based on VAS both at 3 and 6 months. Statistically significant improvements compared to baseline were also reported in IKDC scores and all components of the KOOS questionnaire both at 3 and 6 months post implantation.

Conclusions: These promising clinical results clearly illustrate the early efficacy of this novel meniscus implant for partial meniscus tissue loss. Longer follow-up is however needed to establish its full potential.

Purpose: A three-year evaluation of long-term clinical efficacy of Characterized Chondrocyte Implantation (CCI) compared to microfracture (MF), in the repair of symptomatic cartilage defects of the femoral condyles at 36 months post-surgery.

Materials and Methods: In a prospective, randomized, controlled, multicenter trial, CCI was compared to MF in patients aged 18–50 years with a single symptomatic ICRS grade III–IV lesion of the knee. Clinical outcome was measured 36 months after surgery by means of the KOOS, VAS for pain and ARS, with a non-inferiority margin preset at 9 % points for KOOS and VAS. Furthermore, response to treatment and progression of knee symptoms were assessed. Treatment failure was monitored throughout the study.

Results: Improvement from baseline was higher in the CCI group (N = 41) compared to the MF group (N = 49) for all clinical outcome parameters. Mean improvement from baseline for Overall KOOS was 22.14 vs. 14.48, respectively, with VAS and ARS scores revealing a similar trend. Responder analysis showed 83% of the patients treated with CCI improving vs. 61% after MF. Additionally, we observed a shift in the proportion of knee symptoms over time (52% vs. 35% of asymptomatic knees at 36 months compared to 2% vs. 8% at baseline in the CCI and MF group respectively). At 36 months, failure rates were low in both groups (n=2 in CCI vs. n=7 in MF).

Conclusions: Previous data have described a superior structural repair after CCI compared to MF at 1 year post-surgery. Continued clinical improvement as well as a favorable responder analysis was demonstrated for CCI compared to MF at 36 months.

Introduction: Viscosupplementation is an effective treatment for patients suffering from knee osteoarthritis (OA). Most available products use 3 or 5 injection regimens. The objective of this study was to compare the safety and efficacy of a single 6 mL intra-articular administration of hylan G-F 20 with placebo.

Methods: In this prospective, multicenter, randomized, double-blind study, patients diagnosed with knee OA were randomized to one 6-mL injection of hylan G-F 20 or saline. The primary efficacy analysis (WOMAC A) was performed on the intent-to-treat population and was based on a repeated-measures model over the 26 weeks of the study. The incidence of adverse events (AEs) was collected over the study duration

Results: 253 patients were randomized to hylan G-F 20 (n=124) or placebo (n=129). Mean age was 63 years (42–84), BMI 29.4 (19.5–52.4 kg/m2), 71% were female, and all had primary knee OA of Kellgren Lawrence grade 2 (45%) or 3 (55%). Patients in the hylan G-F 20 group experienced a mean change from baseline in their WOMAC A Likert pain score (0–4 scale) over 26 weeks (primary efficacy criteria) of −0.84, which was statistically significantly different from the change reported in the placebo group (−0.69, p=0.047). Statistically significant differences favoring hylan G-F 20 were also reported for most of the secondary efficacy criteria: WOMAC A1 (estimate Odds Ratio over 26 weeks placebo/hylan G-F 20, 0.64, p=0.013), patient global assessment (0.69, p=0.029), and clinical observer global assessment (0.71, p=0.041); WOMAC B and C changes were not statistically significant between groups. There was no statistically significant difference in the use of rescue medication between the 2 groups. There were no serious AEs related to treatment. In the target knee, injection-related AEs occurred in 4.9% and 3.1% of patients for hylan G-F 20 and placebo, respectively, and treatment-related AEs occurred in 3.3% and 0.8% of patients, respectively. All target knee AEs were local pain, with or without joint swelling or effusion, and were of mild or moderate intensity.

Conclusion: This double-blind placebo-controlled study showed one injection of hylan G-F 20, possibly repeated 6 months later, was safe and provided symptomatic relief lasting up to 6 months in patients with knee OA.

Purpose: The objective of this study was to compare the safety and efficacy of 1 × 6 mL intra-articular administration of hylan G-F 20 with placebo.

Methods: In this prospective, multicenter, randomized, double-blind study, patients diagnosed with knee OA were randomized to one 6-mL injection of hylan G-F 20 or saline. The primary efficacy analysis (WOMAC A) was performed on the intent-to-treat population and was based on a repeated-measures model over the 26 weeks of the study.

Results: 253 patients were randomized to hylan G-F 20 (n=124) or placebo (n=129). Mean age was 63 years (42–84), BMI 29.4 (19.5–52.4 kg/m2), 71% were female, and all had primary knee OA of Kellgren Lawrence grade 2 (45%) or 3 (55%). Patients in the hylan G-F 20 group experienced a mean change from baseline in their WOMAC A Likert pain score (0–4 scale) over 26 weeks (primary efficacy criteria) of −0.84, which was statistically significantly different from the change reported in the placebo group (−0.69, p=0.047). Statistically significant differences favoring hylan G-F 20 were also reported for most of the secondary efficacy criteria: WOMAC A1 (estimate Odds Ratio over 26 weeks placebo/hylan G-F 20, 0.64, p=0.013), patient global assessment (0.69, p=0.029), and clinical observer global assessment (0.71, p=0.041); WOMAC B and C changes were not statistically significant between groups. The OMERACT-OARSI responder analysis indicated that 59% of the patients were responders in the hylan G-F 20 group versus 51% in placebo group (0.66, p=0.059). There was no statistically significant difference in the use of rescue medication (acetaminophen) between the 2 groups.

Discussion and Conclusion: This double-blind placebo-controlled study showed one injection of hylan G-F 20 provided symptomatic relief lasting up to 6 months in patients with knee OA; it avoids the need for multiple injections.

We report a long term experience on massive rotator cuff tears treated by the means of a nonresorbable transosseously fixed patch combined with a subacromial decompression

From December 1996 until August 2002, a total of 41 patients were treated with a synthetic interposition graft and subacromial decompression. All patients had a preoperative ultrasound evidence of a primary massive full-thickness tear that was thought to be irreparable by simple suture. All patients were evaluated pre- and postoperatively using the Constant and Murley score, DASH questionnaire, Simple Shoulder Test, VAS scale for pain, ultrasound and plain radiographs.

The patients consisted of 23 men and 18 women aged 51–80 years (mean 67 years). We had a lost of follow up of 6 patients. One patient had a total shoulder arthroplasty at 7.7 years and one patient had a redo with a new synthetic graft at 9.6 years. They were followed up for a mean of 7.2 years. Their mean preoperative Constant and Murley score improved from 25.7 preoperatively to 69.6. Similar improvements were seen with the DASH score (56.6 to 23.3), SST (1.2 to 7.9) and VAS scale (75.4 to 14.1)

Anatomically, the repair resulted in mean acromio-humeral interval of 6.6 mm. Ultrasound showed a further degeneration of the rotator cuff with tears posteriorly from the interposition graft. In 67.7% of all patients the graft was continuous present. Histology – obtained from one patient scheduled for a reversed shoulder arthroplasty- showed partial ingrowth of peri-tendinous tissue.

Despite ongoing degeneration of the cuff in nearly half our population, restoring a massive rotator cuff defect with a synthetic interposition graft and subacromial decompression can give significant and lasting pain relief with a significant improvement of ADL, range of motion and strength.

Role of ultrasonography in shoulder pathology: Consistency with clinical and operative findings K. W. Chan, G. G. McLeod Department of Trauma and Orthopaedic Surgery, Perth Royal Infirmary, Perth PH1 1NX, United Kingdom.

Shoulder disorders are common and main causes of shoulder pain with/without functional deficit include adhesive capsulitis (frozen shoulder), impingement syndrome and rotator cuff pathology. The sensitivity and specificity of ultrasonography have been reported as 80% and 100% respectively in the literature. We carried out a retrospective case note review of patients that underwent ultrasonography of shoulder, comparing the radiological findings with clinical diagnosis and operative findings. 58 patients, 36 male and 22 female attended the orthopaedic outpatient clinic with painful shoulder and underwent ultrasonography of shoulder during the period of study. Mean age of patients is 55 (range 28 to 78 years old). 33 patients had ultrasonography of right shoulder, 20 patients had ultrasonography of left shoulder while 5 patients had ultrasonography of both shoulders. 79% (50/63) of the ultrasonography findings were consistent with clinical diagnosis. 17 patients had normal findings on ultrasonography and were discharged fully. 25 patients with clinical and radiological diagnosis of biceps tendon tear, calcifying tendinosis and partial/full thickness rotator cuff tear were treated conservatively. 19% (4/21) of patients with diagnosis of calcifying tendinosis had decompression surgery. 38% (8/21) of patients with diagnosis of partial/full thickness rotator cuff tear had decompression surgery + rotator cuff repair. The degree of rotator cuff tear in operative findings for 6 out of 8 patients (75%) that underwent decompression surgery +/− rotator cuff repair were consistent with ultrasonography findings. 4 patients had inconclusive ultrasonography findings and had magnetic resonance imaging to further confirm the pathology. We conclude that ultrasonography should be used as the first line of investigation in aiding the clinical diagnosis and management of shoulder disorders as it is non-invasive and cost effective. The sensitivity of ultrasonography in detecting shoulder pathology is 75% from this study.

The concept of non-anatomic reversed arthroplasty is becoming increasingly popular. The design medializes and stabilizes the center of rotation, and lowers the humerus relative to the acromion, and lengthens the deltoid muscle up to 18%. Such a surgically created global distraction of muscles is likely to affect nervous structures. When nerves are stretched up to 5–10%, axonal transport and nerve conduction starts to be impaired. At 8% of elongation, venous blood flow starts to diminish and at 15% all circulation in and out of the nerve is obstructed. [1] To understand nerve dynamics following reversed arthroplasty, we investigated nerve strain and excursion in a cadaver model.

In a formalin-embalmed female cadaver specimen, the brachial plexus en peripheral upper limb nerves were carefully dissected and injected with an iodine containing contrast medium. At the same time 1.2 mm-diameter leaded markers were implanted at topographically crucial via points for later enhanced recognition on CT reconstructions. After the first session of CT scanning a plastic replica of the Delta reversed shoulder prosthesis® was surgically placed followed by re-injection of the plexus with the same solution. The preoperative and the postoperative specimen were studied using a helical CT scan with a 0,5 mm slice increment. The Mimics® (Materialise NV, Belgium) software package was used for visualization and segmentation of CT images and 3D rendering of the brachial plexus and peripheral nerves.

After surgery, there was an average increase in nerve strain below physiologically relevant amplitudes. In a few local segments of the brachial plexus an increase in nerve strain exceeding 5–10 % was calculated. The largest increase in strain (up to 19%) was observed in a segment of the medial cord. These results suggest there might be a clinically relevant increase in nerve strain following reversed shoulder arthroplasty.

Physiological studies have revealed that the central nervous system controls groups of muscle fibers in a very efficient manner. Within a single skeletal muscle, the central nervous system independently controls individual muscle segments to produce a particular motor outcome. Mechanomyographic studies on the deltoid muscle have revealed that the deltoid muscle, commonly described as having three anatomical segments, is composed of at least seven functional muscle segments, which all have the potential to be at an important level independently coordinated by the central nervous system.[1] In this study we tried to anatomically describe and quantify these different functional segments within the deltoid muscle, based on the branching out pattern of the axillary nerve.

Forty-four deltoids of 22 embalmed adult cadavers, were analyzed. The axillary nerve was carefully dissected together with his anterior and posterior branch upon invasion into the muscle. According to the pattern of fiber distribution and their fascial embalmment, we then carefully splitted the deltoid muscle into different portions each being innervated by a major branch of the axillary nerve. The position and volume of each segment in relation to the whole muscle was derived.

In 3 cases the axillary nerve branched out in 8 major divisions. In 22 out of 44 cases (50%), the axillary nerve branched out in 7 principal parts. A branching out pattern of 6 major divisions occurred in 14 out of 44 cases. Finally we found a division in 5 major branches in 5 of the specimens. In general, both posterior and anterior peripheral segments seemed to have the largest volume. In nearly all (93%) cases, the central segments were smaller in weight and volume compared to the more peripheral segments.

Based on the innervation pattern of the deltoid muscle a segmentation in 5 up to 8 major segments seem to be found. This confirms from anatomical point of view earlier reports of functional differentiation within the deltoid muscle.