Hindfoot varus and neurologic disorders

Muscle imbalance from numerous underlying neurologic disorders can cause dynamic and static hindfoot varus deformity. Most etiologies are congenital, and therefore affect bone morphology and the shape of the foot during growth. Weak and strong muscle groups, bone deformity, and soft-tissue contractures have to be carefully assessed and considered for successful management. Because of the variety of the etiologies and the differences in presentation, treatment decisions in varus hindfoot caused by neurologic disorders must be individualized. Deformity correction includes release of soft tissue contractures, osteotomies and arthrodeses, and tenotomies or tendon transfers to balance muscle strength and prevent recurrence. To decrease elevated anteromedial ankle joint contact stress and provide lateral hindfoot stability during the entire gait cycle, the goal of static and dynamic hindfoot varus realignment is to fully correct all components of the deformity, but particularly the varus tilt of the talus.

Distribution of radiodense contrast medium after perineural injection of the palmar and palmar metacarpal nerves (low 4-point nerve block): an in vivo and ex vivo study in horses

REASONS FOR PERFORMING STUDY: Evidence-based information is limited on distribution of local anaesthetic solution following perineural analgesia of the palmar (Pa) and palmar metacarpal (PaM) nerves in the distal aspect of the metacarpal (Mc) region ('low 4-point nerve block'). OBJECTIVES: To demonstrate the potential distribution of local anaesthetic solution after a low 4-point nerve block using a radiographic contrast model. METHODS: A radiodense contrast medium was injected subcutaneously over the medial or the lateral Pa nerve at the junction of the proximal three-quarters and distal quarter of the Mc region (Pa injection) and over the ipsilateral PaM nerve immediately distal to the distal aspect of the second or fourth Mc bones (PaM injection) in both forelimbs of 10 mature horses free from lameness. Radiographs were obtained 0, 10 and 20 min after injection and analysed subjectively and objectively. Methylene blue and a radiodense contrast medium were injected in 20 cadaver limbs using the same techniques. Radiographs were obtained and the limbs dissected. RESULTS: After 31/40 (77.5%) Pa injections, the pattern of the contrast medium suggested distribution in the neurovascular bundle. There was significant proximal diffusion with time, but the main contrast medium patch never progressed proximal to the mid-Mc region. The radiological appearance of 2 limbs suggested that contrast medium was present in the digital flexor tendon sheath (DFTS). After PaM injections, the contrast medium was distributed diffusely around the injection site in the majority of the limbs. In cadaver limbs, after Pa injections, the contrast medium and the dye were distributed in the neurovascular bundle in 8/20 (40%) limbs and in the DFTS in 6/20 (30%) of limbs. After PaM injections, the contrast and dye were distributed diffusely around the injection site in 9/20 (45%) limbs and showed diffuse and tubular distribution in 11/20 (55%) limbs. CONCLUSIONS AND POTENTIAL RELEVANCE: Proximal diffusion of local anaesthetic solution after a low 4-point nerve block is unlikely to be responsible for decreasing lameness caused by pain in the proximal Mc region. The DFTS may be penetrated inadvertently when performing a low 4-point nerve block.

[Disorders of the origin of the suspensory ligament in the horse: a diagnostic challenge]

Lameness in horses due to pain originating from the proximal metacarpal/metatarsal region remains a diagnostic challenge. In cases of obvious lameness the pain can be localised to this region by diagnostic anaesthesia. Because a variety of disorders can cause lameness in this region different imaging modalities including radiography, ultrasonography and scintigraphy should be used to arrive at an accurate diagnosis. Even though a precise anatomic-pathologic diagnosis can still be an enigma, because not only bone and joints, but also soft tissue structures including the proximal suspensory ligament, its origin at the proximal metacarpus/ metatarsus, its fascia, the superficial fascia, as well as the intermetacarpal/metatarsal ligaments, the accessory ligament of the deep digital flexor tendon and both digital flexor tendons may be involved. Magnet resonance tomography (MRT) shows a high diagnostic sensitivity in imaging soft tissue structures and bone. In horses MRT is still at the beginning. The MRT appearance of the proximal metacarpal/metatarsal region has not yet been evaluated in detail and there are only few anatomic studies of the origin of the suspensory ligament in horses. The first experiences showed, that more gross and histologic examinations are necessary to fully interpret MRT-images and to differentiate pathologic alterations from clinically not relevant variations.

Lesser tuberosity osteotomy for total shoulder arthroplasty. Surgical technique

BACKGROUND: Recent studies have suggested that tenotomy and repair of the subscapularis tendon carried out for anterior approaches to the shoulder can be followed by failure of the tendon repair and by changes resulting in permanent loss of subscapularis function. We hypothesized that release of the subscapularis with use of a superficial osteotomy of the lesser tuberosity followed by repair of the two opposing bone surfaces would lead to consistent bone-to-bone healing, which would be possible to monitor radiographically, and would lead to satisfactory clinical and structural outcomes. METHODS: Thirty-nine shoulders in thirty-six consecutive patients who, at an average age of fifty-seven years, had undergone total shoulder replacement through an anterior approach involving an osteotomy of the lesser tuberosity were evaluated at an average of thirty-nine months. Assessment included a standardized interview and physical examination, scoring according to the system described by Constant and Murley, and imaging with conventional radiography and computed tomography to assess healing of the osteotomy site and changes in the subscapularis. RESULTS: The osteotomized tuberosity fragment healed in an anatomical position in all shoulders, and no cuff tendon ruptures were observed. At the time of follow-up, thirty-three (89%) of thirty-seven shoulders evaluated with a belly-press test had a negative result and twenty-seven (75%) of thirty-six shoulders evaluated with a lift-off test had an unequivocally normal result. Fatty infiltration of the subscapularis muscle increased after the operation (p < 0.0001) and was at least stage two in eleven (32%) of thirty-four shoulders. The fatty infiltration had progressed by one stage in eight (24%) of the thirty-four shoulders, by two stages in five shoulders (15%), and by three stages in two shoulders (6%). CONCLUSIONS: Osteotomy of the lesser tuberosity provides an easy anterior approach for total shoulder replacement and is followed by consistent bone-to-bone healing, which can be monitored, and good subscapularis function. In the presence of documented anatomical healing of the osteotomy site, postoperative fatty infiltration of the subscapularis muscle remains unexplained and needs to be investigated further as it is associated with a poorer clinical outcome.

Long-term outcome after structural failure of rotator cuff repairs

BACKGROUND: In a previous study, twenty consecutive patients with a rerupture of the rotator cuff, as documented with magnetic resonance imaging, were found to have significantly less pain and better function and strength, compared with the preoperative state, at 3.2 years postoperatively. It was the purpose of this study to determine the clinical and structural outcomes of these reruptures in the same twenty patients after a longer period of follow-up. METHODS: At a mean of 7.6 years postoperatively, the twenty patients were reexamined clinically and with standard radiographs and magnetic resonance imaging with use of the same clinical, radiographic, and magnetic resonance imaging criteria as were utilized in the review at 3.2 years. The mean age at the time of final follow-up was sixty-six years. RESULTS: Nineteen of the twenty patients continued to be either very satisfied or satisfied with the outcome. The relative Constant score averaged 88% and was not significantly different from the score at 3.2 years, which averaged 83%. The mean scores for pain, function, and strength also had not changed significantly. Overall, the twenty reruptures had not increased in size, and eight of them had healed structurally at the time of the 7.6-year follow-up. Seven of these eight reruptures had been of the supraspinatus tendon only, and seven had been smaller than 400 mm(2) at 3.2 years. Twelve reruptures persisted, and five were larger than the preoperative tear. Fatty infiltration of the infraspinatus muscle progressed significantly (p = 0.015) and the acromiohumeral distance decreased significantly (p = 0.006) between the two follow-up periods. Neither fatty infiltration of the supraspinatus and subscapularis muscles nor glenohumeral osteoarthritis progressed significantly. CONCLUSIONS: At an average of 7.6 years, the clinical outcomes after structural failure of rotator cuff repairs remained significantly improved over the preoperative state in terms of pain, function, strength, and patient satisfaction. Overall, the reruptures that had been present at 3.2 years did not increase in size. We also found that reruptures of the supraspinatus that had been smaller than 400 mm(2) had the potential to heal.

Multilineage differentiation potential of equine blood-derived fibroblast-like cells

Tissue engineering (TE) has emerged as a promising new therapy for the treatment of damaged tissues and organs. Adult stem cells are considered as an attractive candidate cell type for cell-based TE. Mesenchymal stem cells (MSC) have been isolated from a variety of tissues and tested for differentiation into different cell lineages. While clinical trials still await the use of human MSC, horse tendon injuries are already being treated with autologous bone marrow-derived MSC. Given that the bone marrow is not an optimal source for MSC due to the painful and risk-containing sampling procedure, isolation of stem cells from peripheral blood would bring an attractive alternative. Adherent fibroblast-like cells have been previously isolated from equine peripheral blood. However, their responses to the differentiation conditions, established for human bone marrow MSC, were insufficient to fully confirm their multilineage potential. In this study, differentiation conditions were optimized to better evaluate the multilineage capacities of equine peripheral blood-derived fibroblast-like cells (ePB-FLC) into adipogenic, osteogenic, and chondrogenic pathways. Adipogenic differentiation using rabbit serum resulted in a high number of large-size lipid droplets three days upon induction. Cells' expression of alkaline phosphatase and calcium deposition upon osteogenic induction confirmed their osteogenic differentiation capacities. Moreover, an increase of dexamethasone concentration resulted in faster osteogenic differentiation and matrix mineralization. Finally, induction of chondrogenesis in pellet cultures resulted in an increase in cartilage-specific gene expression, namely collagen II and aggrecan, followed by protein deposition after a longer induction period. This study therefore demonstrates that ePB-FLC have the potential to differentiate into adipogenic, osteogenic, and chondrogenic mesenchymal lineages. The presence of cells with confirmed multilineage capacities in peripheral blood has important clinical implications for cell-based TE therapies in horses.

Correlation of atrophy and fatty infiltration on strength and integrity of rotator cuff repairs: a study in thirteen patients

In 13 patients, the development of supraspinatus muscle atrophy and fatty infiltration after rotator cuff tendon repair was quantified prospectively via magnetic resonance imaging. Intraoperative electrical nerve stimulation at repair showed that the maximal supraspinatus tension (up to 200 N) strongly correlated with the anatomic cross-sectional muscle area and with muscle fatty infiltration (ranging from 12 N/cm(2) in Goutallier stage 3 to 42 N/cm(2) in Goutallier stage 0). Within 1 year after successful tendon repair (n = 8), fatty infiltration did not recover, and atrophy improved partially at best; however, if the repair failed (n = 5), atrophy and fatty infiltration progressed significantly. The ability of the rotator cuff muscles to develop tension not only correlates with their atrophy but also closely correlates with their degree of fatty infiltration. With current repair techniques, atrophy and fatty infiltration appear to be irreversible, despite successful tendon repair. Unexpectedly, not only weak but also very strong muscles are at risk for repair failure.

The "flap-shaft" prosthesis for insensate feet with Chopart or Lisfranc amputations

BACKGROUND: The inevitable detachment of tendons and the loss of the forefoot in Chopart and Lisfranc amputations result in equinus and varus of the residual foot. In an insensate foot these deformities can lead to keratotic lesions and ulcerations. The currently available prostheses cannot safely counteract the deforming forces and the resulting complications. METHODS: A new below-knee prosthesis was developed, combining a soft socket with a rigid shaft. The mold is taken with the foot in the corrected position. After manufacturing the shaft, the lateral third of the circumference of the shaft is cut away and reattached distally with a hinge, creating a lateral flap. By closing this flap the hindfoot is gently levered from the varus position into valgus. Ten patients (seven amputations at the Chopart-level, three amputations at the Lisfranc-level) with insensate feet were fitted with this prosthesis at an average of 3 (range 1.5 to 9) months after amputation. The handling, comfort, time of daily use, mobility, correction of malposition and complications were recorded to the latest followup (average 31 months, range 24 to 37 months after amputation). RESULTS: Eight patients evaluated the handling as easy, two as difficult. No patient felt discomfort in the prosthesis. The average time of daily use was 12 hours, and all patients were able to walk. All varus deformities were corrected in the prosthesis. Sagittal alignment was kept neutral. Complications were two minor skin lesions and one small ulcer, all of which responded to conservative treatment, and one ulcer healed after debridement and lengthening of the Achilles tendon. CONCLUSIONS: The "flap-shaft" prosthesis is a valuable option for primary or secondary prosthetic fitting of Chopart-level and Lisfranc-level amputees with insensate feet and flexible equinus and varus deformity at risk for recurrent ulceration. It provided safe and sufficient correction of malpositions and enabled the patients to walk as much as their general condition permitted.

Traumatische chronische Instabilität des proximalen Tibiofibulargelenkes [Traumatic chronic instability of the proximal tibiofibular joint]

The rare condition of chronic instability of the proximal tibiofibular joint can be of traumatic or idiopathic origin and can lead to secondary arthritis. After conservative treatment for 6 months and persistent pain, operative treatment should be considered. We present a case of traumatic instability, ligament reconstruction with a part of the biceps femoris tendon, and postoperative return to full and painless sport activities.

In vivo biochemical 7.0 Tesla magnetic resonance: preliminary results of dGEMRIC, zonal T2, and T2* mapping of articular cartilage

INTRODUCTION: Ultra-high-field whole-body systems (7.0 T) have a high potential for future human in vivo magnetic resonance imaging (MRI). In musculoskeletal MRI, biochemical imaging of articular cartilage may benefit, in particular. Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) and T2 mapping have shown potential at 3.0 T. Although dGEMRIC, allows the determination of the glycosaminoglycan content of articular cartilage, T2 mapping is a promising tool for the evaluation of water and collagen content. In addition, the evaluation of zonal variation, based on tissue anisotropy, provides an indicator of the nature of cartilage ie, hyaline or hyaline-like articular cartilage.Thus, the aim of our study was to show the feasibility of in vivo dGEMRIC, and T2 and T2* relaxation measurements, at 7.0 T MRI; and to evaluate the potential of T2 and T2* measurements in an initial patient study after matrix-associated autologous chondrocyte transplantation (MACT) in the knee. MATERIALS AND METHODS: MRI was performed on a whole-body 7.0 T MR scanner using a dedicated circular polarization knee coil. The protocol consisted of an inversion recovery sequence for dGEMRIC, a multiecho spin-echo sequence for standard T2 mapping, a gradient-echo sequence for T2* mapping and a morphologic PD SPACE sequence. Twelve healthy volunteers (mean age, 26.7 +/- 3.4 years) and 4 patients (mean age, 38.0 +/- 14.0 years) were enrolled 29.5 +/- 15.1 months after MACT. For dGEMRIC, 5 healthy volunteers (mean age, 32.4 +/- 11.2 years) were included. T1 maps were calculated using a nonlinear, 2-parameter, least squares fit analysis. Using a region-of-interest analysis, mean cartilage relaxation rate was determined as T1 (0) for precontrast measurements and T1 (Gd) for postcontrast gadopentate dimeglumine [Gd-DTPA(2-)] measurements. T2 and T2* maps were obtained using a pixelwise, monoexponential, non-negative least squares fit analysis; region-of-interest analysis was carried out for deep and superficial cartilage aspects. Statistical evaluation was performed by analyses of variance. RESULTS: Mean T1 (dGEMRIC) values for healthy volunteers showed slightly different results for femoral [T1 (0): 1259 +/- 277 ms; T1 (Gd): 683 +/- 141 ms] compared with tibial cartilage [T1 (0): 1093 +/- 281 ms; T1 (Gd): 769 +/- 150 ms]. Global mean T2 relaxation for healthy volunteers showed comparable results for femoral (T2: 56.3 +/- 15.2 ms; T2*: 19.7 +/- 6.4 ms) and patellar (T2: 54.6 +/- 13.0 ms; T2*: 19.6 +/- 5.2 ms) cartilage, but lower values for tibial cartilage (T2: 43.6 +/- 8.5 ms; T2*: 16.6 +/- 5.6 ms). All healthy cartilage sites showed a significant increase from deep to superficial cartilage (P < 0.001). Within healthy cartilage sites in MACT patients, adequate values could be found for T2 (56.6 +/- 13.2 ms) and T2* (18.6 +/- 5.3 ms), which also showed a significant stratification. Within cartilage repair tissue, global mean values showed no difference, with 55.9 +/- 4.9 ms for T2 and 16.2 +/- 6.3 ms for T2*. However, zonal assessment showed only a slight and not significant increase from deep to superficial cartilage (T2: P = 0.174; T2*: P = 0.150). CONCLUSION: In vivo T1 dGEMRIC assessment in healthy cartilage, and T2 and T2* mapping in healthy and reparative articular cartilage, seems to be possible at 7.0 T MRI. For T2 and T2*, zonal variation of articular cartilage could also be evaluated at 7.0 T. This zonal assessment of deep and superficial cartilage aspects shows promising results for the differentiation of healthy and affected articular cartilage. In future studies, optimized protocol selection, and sophisticated coil technology, together with increased signal at ultra-high-field MRI, may lead to advanced biochemical cartilage imaging.

The clinical and structural long-term results of open repair of massive tears of the rotator cuff

BACKGROUND: At a mean follow-up of 3.1 years, twenty-seven consecutive repairs of massive rotator cuff tears yielded good and excellent clinical results despite a retear rate of 37%. Patients with a retear had improvement over the preoperative state, but those with a structurally intact repair had a substantially better result. The purpose of this study was to reassess the same patients to determine the long-term functional and structural results. METHODS: At a mean follow-up interval of 9.9 years, twenty-three of the twenty-seven patients returned for a review and were examined clinically, radiographically, and with magnetic resonance imaging with use of a methodology identical to that used at 3.1 years. RESULTS: Twenty-two of the twenty-three patients remained very satisfied or satisfied with the result. The mean subjective shoulder value was 82% (compared with 80% at 3.1 years). The mean relative Constant score was 85% (compared with 83% at 3.1 years). The retear rate was 57% at 9.9 years (compared with 37% at 3.1 years; p = 0.168). Patients with an intact repair had a better result than those with a failed reconstruction with respect to the mean absolute Constant score (81 compared with 64 points, respectively; p = 0.015), mean relative Constant score (95% and 77%; p = 0.002), and mean strength of abduction (5.5 and 2.6 kg; p = 0.007). The mean retear size had increased from 882 to 1164 mm(2) (p = 0.016). Supraspinatus and infraspinatus muscle fatty infiltration had increased (p = 0.004 and 0.008, respectively). Muscles with torn tendons preoperatively showed more fatty infiltration than muscles with intact tendons preoperatively, regardless of repair integrity. Shoulders with a retear had a significantly higher mean acromion index than those without retear (0.75 and 0.65, respectively; p = 0.004). CONCLUSIONS: Open repair of massive rotator cuff tears yielded clinically durable, excellent results with high patient satisfaction at a mean of almost ten years postoperatively. Conversely, fatty muscle infiltration of the supraspinatus and infraspinatus progressed, and the retear size increased over time. The preoperative integrity of the tendon appeared to be protective against muscle deterioration. A wide lateral extension of the acromion was identified as a previously unknown risk factor for retearing.

Dynamic repair of scapholunate dissociation with dorsal extensor carpi radialis longus tenodesis

This study investigates the results of a technique using an extensor carpi radialis longus (ECRL) tenodesis for symptomatic scapholunate instability. Symptomatic scapholunate instability has been corrected so far either by limited wrist fusion or by various techniques of soft tissue repair. Limited wrist fusion greatly reduces wrist motion and increases the probability of osteoarthritis in the remaining mobile wrist segments. On the other hand, most types of soft tissue repair are technically difficult to perform and have disappointing results due to the inherent laxity. The presented dynamic approach was used in 20 wrists of 19 patients with static scapholunate instability. Preoperative evaluation included in all patients clinical examination, radiologic evaluation, and arthroscopy for establishing the diagnosis of static scapholunate instability. The technique involves the fixation of the ECRL tendon on the dorsal aspect of the scaphoid by means of a cancellous screw and a special washer. Dynamic ECRL tenodesis of the scaphoid is a safe and simple procedure that enhances the extension forces on the scaphoid in all wrist positions. The results of this preliminary report in 20 wrists showed dynamic ECRL tenodesis to be an effective treatment option for treating symptomatic static scapholunate instability.

Versatility of the abductor hallucis muscle as a conjoined or distally-based flap

Soft tissue coverage of the medial ankle and foot remains a difficult, challenging, and often frustrating problem to patients as well as surgeons. To our knowledge, the abductor hallucis muscle flap is not frequently used and only a few well documented cases were found in literature. The purpose of this paper is to report and to present the long-term results of a series of four patients who underwent reconstruction of foot and ankle defects with the abductor hallucis muscle flap.In two cases, the abductor hallucis muscle flap was transposed in combination with a medialis pedis flap to cover a medial ankle defect, whereas in another case it was combined with a medial plantar flap. In this latter case, the muscle flap served to fill up a calcaneal dead space after osteomyelitis debridement, whereas the cutaneous flap was used to replace debrided skin at the heel. The abductor hallucis flap was used as a distally-based turnover flap to cover a large forefoot defect in a fourth case. Follow-up period ranged between 18 and 64 months (mean 43.3). In the early postoperative period, two flaps healed completely In two patients marginal flap necrosis occurred which was subsequently skin grafted. No donor-site complication occurred in any of the patients. In all cases, protective sensation of the skin was satisfactory as early as 6 months. In two cases mild hyperkeratosis at the skin graft border to the sole skin (non-weight bearing area of medial plantar and medialis pedis flap donor site) was present, but probably related to poor foot care. All patients were fully mobile as early as 3 months after treatment. In the long-term follow-up (43.3 months), all flaps provided with durable coverage. Functional gait deficit due to consumtion of the abductor hallucis muscle was not apparent.Our long-term results demonstrated that the abductor hallucis muscle flap is a versatile, and reliable flap suitable for the reconstruction of foot and ankle defects. Utilizing the abductor hallucis muscle as a pedicled flap (distally or proximally-based) with or without conjoined regional fasciocutaneous flaps offers a successful and durable alternative to microsurgical tree flaps for small to moderate defects over the calcaneus region, medial ankle, medial foot, and forefoot with exposed bone, tendon, or joint.

Lateral meniscal cyst causing common peroneal palsy

Lateral meniscal cysts are relatively common, but only in rare instances do they cause common peroneal nerve irritation. There are, we believe, no cases reported in which both the sensory and motor functions of the nerve have been compromised. We present a case of a lateral meniscal cyst that became palpable and led to symptoms of numbness and weakness in the distribution of the common peroneal nerve. The MRI findings were of an oblique tear of the lateral meniscus with an associated multiloculated meniscal cyst that coursed behind the biceps tendon before encroaching on the common peroneal nerve. Surgical resection confirmed the tract as located on the MRI and histology confirmed the mass to be a synovial cyst. Resection of the cyst and arthroscopic excision of the meniscal tear led to resolution of the symptoms in 3 months.

Neer Award 2007: Reversion of structural muscle changes caused by chronic rotator cuff tears using continuous musculotendinous traction. An experimental study in sheep

HYPOTHESIS: Chronic rotator cuff tears are associated with irreversible architectural muscle changes and a high rate of repair failure. The changes observed in man and their irreversibility with a single stage repair can be reproduced in sheep. It was the purpose of this experiment to test the hypothesis that slow, continuous elongation of a retracted musculotendinous unit allows reversal of the currently irreversible structural muscle changes. MATERIALS AND METHODS: The infraspinatus tendon of 12 sheep was released using a greater tuberosity osteotomy and allowed to retract for 4 months. Then, a new device was mounted on the scapular spine and used to extend the infraspinatus muscuculotendinous unit transcutaneously by 1 mm per day. Thereafter, the tendon was repaired back to the greater tuberosity. We assessed the muscular architecture using magnetic resonance imaging, macroscopic dissection, histology, and electron microscopy. Fatty infiltration (in Hounsfield units 1/4 HU) and muscular cross-sectional area (in % of the control side) were monitored with computed tomography at tendon release, initiation of elongation, repair, and at sacrifice. RESULTS: Sixteen weeks after tendon release, the mean tendon retraction was 29 +/- 6 mm (14% of original length, P = .008). In 8 sheep, elongation was achieved as planned (group I), but in 4, the elongation failed technically (group II). The mean traction time was 24 +/- 6 days with a mean traction distance of 19 +/- 4 mm. At sacrifice, the mean pennation angle in the infraspinatus of group I was not different from the control side (29.8 degrees +/-7.5 degrees vs. 30 degrees +/-6 degrees , P = .575). In group II, the pennation angle had increased from 30 degrees +/-6 degrees to 55 degrees +/-14 degrees (P = .035). There was no fatty infiltration at the time of tendon release. After retraction, there was a significant increase in fatty infiltration of the infraspinatus muscle and a decrease of its cross-sectional area to 57% of the contralateral side (P = .0001). During traction, the degree of fatty infiltration remained unchanged (36 HU to 38 HU, P = .381), and atrophy improved to a muscle square area of 78% of the contralateral side (P = .0001) in group I. In group II, an increase of fatty infiltration was measured from 36 HU to 28 HU; however, this increase was not significant (P = .144). Atrophy did not change in group II (57-55%, P = .946). At sacrifice, the remaining muscle mass was 64% in group I and 46% in group II (P = .019). DISCUSSION: Our preliminary results document, that continuous elongation of a retracted, fatty infiltrated and atrophied musculotendinous unit is technically feasible. CONCLUSION: In the sheep, continuous elongation can lead to restoration of normal muscle architecture, to partial reversal of muscle atrophy, and to arrest of the progression of fatty infiltration. LEVEL OF EVIDENCE: Basic science level 2; Prospective comparative therapeutic study.