Biochemistry and biomechanics of healing tendon: Part II. Effects of combined laser therapy and electrical stimulation

Twenty-two closed Achilles tendon ruptures caused by sports injuries in 22 patients (average age, 37.6 years) were repaired with Kirschmayer core suture and cross-stitch epitenon suture, and early active ankle motion with weightbearing was implemented after surgery. This study was undertaken to evaluate the effectiveness of the repair technique and rehabilitation protocol by assessing clinical results and magnetic resonance imaging findings. The follow-up period averaged 24.6 months. Twenty of the tendons (91%) healed without rerupture, and two tendons (9%) suffered a partial rerupture at 23 and 56 days, respectively. Active ankle extension reached from the minus range to 0 degree in an average of 9.7 days, and ankle motion recovered to normal in an average of 6.0 weeks. Full weightbearing without heel raising became possible in an average of 16.4 days, and heel raising with both legs became possible in an average of 7.3 weeks. The patients returned to full sports activity in 13.1 weeks. The interval until the area of high-intensity signal at the tendon repair site on T2-weighted magnetic resonance imaging scans became intermediate-intensity signal averaged 6.9 weeks, and the tendon repair site became low-intensity signal in an average of 12.6 weeks, demonstrating excellent tendon healing. Treatment employing Kirschmayer core suture and cross-stitch epitenon suture may help athletes return to sports activity in a shorter period than that allowed by previous methods of repair for Achilles tendon ruptures.     

Propofol bolus facilitates reduction of luxed temporomandibular joints

All patients with badminton-related acute Achilles tendon ruptures registered during 1990 to 1994 at the University Hospital of Ume? were retrospectively followed up using a questionnaire. Thirty-one patients (mean age, 36.0 years), 27 men and 4 women, were included. Thirty patients (97%) described themselves as recreational players or beginners. The majority of the injuries (29 of 31, 94%) happened at the middle or end of the planned game. Previous local symptoms had been noticed by five patients (16%). Long-term results showed that patients treated with surgery had a significantly shorter sick leave absence than patients treated without surgery (50 versus 75 days). There was no obvious selection favoring any treatment modality. None of the surgically treated patients had reruptures, but two reruptures occurred in the nonsurgically treated group. There seemed to be fewer remaining symptoms and a higher sports activity level after the injury in the surgically treated group. Our results indicate that local muscle fatigue may interfere with strength and coordination. Preventive measures such as specific treatment of minor injuries and adequate training of strength, endurance, and coordination are important. Our findings also indicate that surgical treatment and careful postoperative rehabilitation is of great importance among badminton players of any age or sports level with Achilles tendon rupture.     

Conservative functional therapy of closed rupture of the Achilles tendon. Treatment approach and analysis of results

In a prospective study in the period from May 1989 to April 1994, 161 patients at the Unfallchirurgische Klinik in Braunschweig were treated for rupture of the Achilles tendon using a conservative functional method. A follow-up examination was carried out on 132 patients (81%) after an average of 12.6 months. Conservative therapy was indicated if dynamic ultrasonography showed sufficient adaptation of the rupture. Continuous retention of the adapted tendon fragments was guaranteed by means of special footwear that raises the back of the foot (Variostabil). The average age of the patients was 39.5 years. In 97 cases (73.5%) the injury was caused by sports. In 68 ruptures the dehiscence was compensated in plantar flexion. In 48 cases the dehiscence was 1-5 mm, and in 16 cases it was between 6 and 10 mm. The average period of hospitalization was 4.8 days (1/19). The period of inability to work was an average of 4 weeks (27.4 days (0/98)). The rupture healed on an average of 9.5 weeks (5.9/23). Complications included seven cases of re-rupture (5.3%), and, in the course of treatment, four patients (3%) suffered profound leg vein thrombosis that in one case developed into postthrombotic syndrome. In two cases there was tendovaginitis of the Achilles tendon. Early functional conservative therapy using the VARIO-STABIL shoe is a suitable method for treating a newly ruptured Achilles tendon. When there is a precise indication, the method is equally as good as operative therapy and because of the low complication rate, it is even preferable.     

Achilles tendon rupture. Surgical or non-surgical treatment

Opinions differ about the proper treatment of Achilles tendon rupture. 38 patients with acute total rupture of the Achilles tendon were included in a comparative study of operative as against non-operative treatment. 21 of the patients were treated operatively and 17 non-operatively. The follow-up time was 6-53 months. Three of the non-operated patients but none of the operated group experienced major complications. Ten of the non-operated patients and 14 of the non-operated group experienced minor complications. In the non-operated patients the plantar-flexion range was significantly reduced in the injured foot compared with the other foot (p = 0.03). Because of more re-ruptures and reduced muscle strength in the non-operative group, operative treatment is recommended for active persons. Non-operative treatment may be considered for older people.     

Outcome and prognostic factors of achilles rupture repair using a new scoring method

A new clinical scoring system, including subjective assessment of symptoms and evaluation of ankle range of motion and isokinetic measurement of ankle plantar flexion and dorsiflexion strengths, is presented in 101 patients (86 men, 15 women) who had repair of a closed Achilles tendon rupture. Twenty-one patients were competitive athletes and 70 were recreational athletes. Eighty-one percent of the ruptures were related to sports, and 32% occurred while playing volleyball. Twenty-six patients had previous Achilles tendon symptoms. At followup, an average of 3.1 years after repair, the overall result scores were excellent in 34 cases, good in 46, fair in 17, and poor in four. Only age was a predictor of overall results. The isokinetic strength scores were excellent or good in 72 cases, fair in 18, and poor in 11. Presence of systemic diseases, activity level, previous Achilles tendon symptoms, and later return to physical exercise were predictors of strength results. Gender, body weight, height, period between rupture and operation, surgeon, rupture site, operative method, complications, and thickness, width, and area of the Achilles tendon at followup were not related significantly to the outcome.     

Sensitivity of H-reflexes and stretch reflexes to presynaptic inhibition in humans

The sensitivity of soleus H-reflexes, T-reflexes, and short-latency stretch reflexes (M1) to presynaptic inhibition evoked by a weak tap applied to the biceps femoris tendon or stimulation of the common peroneal nerve (CPN) was compared in 17 healthy human subjects. The H-reflex was strongly depressed for a period lasting up to 300-400 ms (depression to 48 +/- 23%, mean +/- SD, of control at a conditioning test interval of 70 ms) by the biceps femoris tendon tap. In contrast, the short-latency soleus stretch reflex elicited by a quick passive dorsiflexion of the ankle joint was not depressed. The soleus T-reflex elicited by an Achilles tendon tap was only weakly depressed (92 +/- 8%). The H-reflex was also significantly more depressed than the T-reflex at long intervals (>15 ms) after stimulation of CPN (H-reflex 63 +/- 14%, T-reflex 91 +/- 13%; P < 0. 01). However, the short-latency (2 ms) disynaptic reciprocal Ia inhibition evoked by stimulation of CPN was equally strong for H- and T-reflexes (H-reflex 72 +/- 10%, T-reflex 67 +/- 13%; P = 0.07). Peaks in the poststimulus time histogram (PSTH) of the discharge probability of single soleus motor units (n = 53) elicited by an Achilles tendon tap had a longer duration than peaks evoked by electrical stimulation of the tibial nerve (on average 5.0 ms as compared with 2.7 ms). All parts of the electrically evoked peaks were depressed by the conditioning biceps femoris tendon tap (average depression to 55 +/- 27% of control; P < 0.001). A similar depression was observed for the initial 2 ms of the peaks evoked by the Achilles tendon tap (69 +/- 48%; P < 0.001), but the last 2 ms were not depressed. Conditioning stimulation of the CPN at long intervals (>15 ms) also depressed all parts of the electrically evoked PSTH peaks (n = 34; average 65%; P < 0.001) but had only a significant effect on the initial 2 ms of the peaks evoked by the Achilles tendon tap (85%; P < 0.001). We suggest that the different sensitivity of mechanically and electrically evoked reflexes to presynaptic inhibition is caused by a difference in the shape and composition of the excitatory postsynaptic potentials underlying the two reflexes. This difference may be explained by a different composition and/or temporal dispersion of the afferent volleys evoked by electrical and mechanical stimuli. We conclude that it is not straightforward to predict the modulation of stretch reflexes based on observations of H-reflex modulation.     

Balloon extraction of esophageal foreign bodies in children

A study to determine the sensitivity, specificity, and positive and negative predictive values of several clinical diagnostic tests of subcutaneous Achilles tendon rupture was performed during a 13-year period. There were 174 patients with clinical diagnosis of unilateral complete subcutaneous Achilles tendon tear and 28 patients with unilateral suspected but no actual Achilles tendon tear. The following tests were used: palpation, calf squeeze, Matles, Copeland, and O'Brien. Palpation of the gap was the least sensitive clinical test with the patient awake (0.73), increasing to 0.81 when the test was performed under anesthesia; the Copeland and O'Brien tests showed a sensitivity of 0.8. Both the calf squeeze and Matles tests were significantly more sensitive than the other tests (0.96 and 0.88, respectively; 0.022 < P < 0.05). All tests showed a high positive predictive value, with no statistically significant difference between the various tests. In the 28 patients with no evidence of a subcutaneous Achilles tendon tear on imaging, the tests showed a high capability to detect that the Achilles tendon was intact (gap palpation specificity, 0.89; calf squeeze test specificity, 0.93; Matles test specificity, 0.85). Whichever tests were performed, at least two of them were positive for a subcutaneous tear of the Achilles tendon in all patients in this study.     

Can sonography predict the outcome in patients with achillodynia?

PURPOSE: We evaluated whether the grade assigned to the Achilles tendon's appearance on sonograms can be used to predict the outcome of achillodynia. METHODS: A retrospective evaluation was done of a case series of patients with Achilles tendon pain seen at a sports medicine clinic. The study consisted of chart reviews, telephone follow-up interviews, and grading of ultrasound images of the tendon obtained during the initial visit. The grading scheme was as follows: grade 1, normal tendon; grade 2, enlarged tendon; and grade 3, tendon containing a hypoechoic area, regardless of size. The time needed to recover from symptoms was compared between grades using survival analysis. RESULTS: The group consisted of 33 patients, with a mean age of 35.8 years and a mean follow-up time of 24.3 months. There was a statistically significant difference in the time to full recovery between grades (p = 0.02). Patients with grade 1 tendons had a prompter resolution of symptoms than did patients with grade 2 or 3 tendons. CONCLUSIONS: This retrospective study of the outcome of achillodynia demonstrates the possible use of tendon sonography as a prognostic tool to supplement physical examination.     

Bottle injuries in Denmark 1991-1995

In the period from 1991-95, 1843 injuries caused by bottles were reported to the Danish EHLASS register, the latter representing 14.2% of the total number of patients seen in the Emergency Room in Denmark. The reports were classified as sharp or blunt injuries; age, sex, and body localisation were registered, and the injuries were grouped into eight body localisations. Hand injuries made up largest group (62%), and of these 92% were sharp injuries. The rest of the injuries (38%) were spread over the other zones, each representing 3-11%. Among the injuries there was a significant overrepresentation of males and young people between 10-24 years of age. Nearly 30% of the injuries were associated with a fall. We estimate that the total number of injuries caused by bottles was 2596/year, and that the incidence rate was 4.98/10,000 person years.     

The resection of gastrocnemius muscles in aesthetically disturbing calf hypertrophy

In some patients, oversized calves lead to mental distress and avoidance of certain social activities. They hide their legs in pants and seek medical advice. If the thickness of the subcutaneous fat is normal and cannot be diminished by liposuction, the oversized calves are caused by pure muscle hypertrophy. Using the gastrocnemius for muscle flaps in covering knee defects does not impair the function of the patient's leg; therefore, resection of the total gastrocnemius muscle for aesthetic calf reduction was performed in 15 consecutive patients without any lasting impairment with stability or sports activities. The patient was placed in a prone position, and the muscles were bluntly freed and pulled through two incisions of 5-cm length in the hollow of the knee and above the Achilles tendon. The resected muscles weighed between 410 and 810 g each. In two patients, the sural nerve was stretched or cut during the operation. The consequent numbness of the lateral ankle and sole persisted for 9 and 13 months, respectively. All 15 patients were satisfied with the results; none complained of lack of stability or insecurity in walking; and all became active in sports or changed their dress habits.     

Some biomechanical aspects of the foot and ankle in athletes with and without shin splints

Thirteen adult male athletes (long-distance runners and orienteerers without foot problems) and 35 male athletes with shin splints were compared with respect to: 1) the position of the lower leg and the heel while standing, 2) the passive range of mobility in the subtalar joint, and 3) the angular displacement between the calcaneus and the midline of the lower leg (Achilles tendon angle) while running with bare feet on a treadmill. In standing, the two groups differed statistically significantly in the Achilles tendon angle, which values were greater in the shin splint group. With respect to passive mobility, the athletes with shin splints had significantly greater (P less than 0.05-0.01) angular displacement values in inversion, eversion, and in their sum than the control group. While running, the Achilles tendon angle of the shin splint group was significantly greater (P less than 0.01) at the heel strike. Further, the shin splints group had a significantly greater (P less than 0.01) angular displacement between the heel strike and the maximal everted position. The results suggest structural and functional differences in the feet and ankles between healthy athletes and those with shin splints.     

Valproic acid treatment of epilepsy in autistic twins

Ultrasound-guided percutaneous core biopsy technique was studied in 15 consecutive patients with chronic Achilles tendon disorder defined as persisting local pain during daily activities, localized pain and swelling on palpation 2-5 cm proximal to the calcaneal insertion. Ultrasound verified widening of the tendon and low echogenous areas at the site of pain. Percutaneous biopsies were taken from both the low echogenous areas and the normoechogenic tendon tissue. Of 104 core biopsies 99 were representative. Open biopsies were taken from the macroscopically injured and normal tendon for comparison. Core and open biopsies of the low echogenous and macroscopically injured tendon showed similar histopathology. In 10 patients the core biopsy was performed under local anesthesia with limited subjective symptoms. Five of these patients were operated 18-41 days later. No adverse effect was found referring to the biopsy taken a few weeks prior to surgery. No complications occurred. We conclude that the percutaneous core biopsy, guided by ultrasound and performed under local anesthesia, can be used under clinical and experimental in vivo studies for improving knowledge on pathoanatomy and healing processes of the Achilles tendon.     

The treatment of prolactinomas during pregnancy and the lactation period

Thanks to its good long-term results, surgery is the method of choice to treat subcutaneous ruptures of the Achilles tendon. Reconstructed tendons present typical morphological and functional US patterns which depend partly on the kind of surgical reconstruction and partly on the time passed since surgery. The authors report the results of the clinical and US follow-up of a series of 62 surgical patients treated in 7 years for the subcutaneous rupture of the Achilles tendon. The patients were 55 men and 7 women, whose mean age was 36 years (range: 25-65 years). The left-hand side was affected in 38 patients and the right-hand side in 24 patients. All patients were operated on using an end-to-end suture and reinforcement plastic surgery pulling down a gastrocnemius tendon flap. To homogenize the results, all the US exams were performed by the same operator, in the presence of the orthopedic specialist and under the same conditions: both the involved and the contralateral Achilles tendons were studied, longitudinal and transverse scans were performed with the foot in max. plantar and dorsal flexion and, whenever possible, dynamic scans were also performed making the sural triceps contract against resistance. The following parameters were studied clinically: pain (which was absent in 39 patients, occasional in 11, after stress in 9 and on walking in 3 patients), skin scar trophism (which was eutrophic in 53.23% of patients, keloid in 27.42% and hypertrophic in 19.35% of patients), ankle joint excursion (plantar flexion was impaired in 32.3% and dorsal flexion in 36% of patients), walking on tiptoe (in all, 22.6% of patients complained of difficulties walking on tiptoe) and, finally, work activity resumption (which all patients achieved). US depicted the surgical tendons as much bigger than the contralateral ones (3-4 times on the average), which increase in volume lasted throughout the follow-up. In 75% of patients the echo structure of the surgical tendons was inhomogeneous, with scattered hypoechoic and hyperechoic areas. In the extant 25% of patients, nearly all of them followed-up for over 6 years, US depicted a clear-cut hyperechoic area whose size and echo structure were similar to the healthy tendons'. Our results strongly suggest that tenorrhaphy and flap plastic surgery be used to repair subcutaneous ruptures of the Achilles tendon. US proved to be the most reliable and feasible method also in the follow-up. The US images of the patients submitted to surgery more than 6 years earlier revealed fibrillate reorganization patterns and tendon restructuring. These processes involve both ends of the sutured tendon and not the reinforcement flap, which further confirms the exclusively mechanical, and not biological, function of the latter.     

Discharge pattern of single motor units in the tonic vibration reflex of human triceps surae

Using a single fibre EMG electrode the firing pattern of 46 motor units in the triceps surae has been studied during vibration of the Achilles tendon at frequencies of 25--200 Hz. Potentials activated in the tonic vibration reflex (TVR) were phase-locked to the vibration cycle but tended to become somewhat less so with continued vibration. The firing pattern of voluntarily activated motor units became locked to the waveform by the application of the vibrator. The discharges of 21 motor units were studied during low threshold (sub-M wave) tetanic stimulation of the tibial nerve at 25--100 Hz. No evidence was found of synchronization of potentials activated in the resulting tonic contraction. During weak voluntary contractions, stimulation also failed to regularize voluntarily activated motor units. The findings can be reconciled by postulating that, in normal man, vibration activates monosynaptic and polysynaptic pathways, the latter circuit being adequate to generate reflex contraction, while the former merely affects the temporal patterning of the motor outflow.     

Epidemiology of school injuries in the northern part of Sweden

The aim of this one-year investigation of school accidents is to obtain more knowledge for preventive work. In the age-group 7-19 years, 547 injuries were registered, mainly at three hospitals. The incidence rate was 25 per 1000 boys and 20 per 1000 girls per year. Most injuries occurred in intermediate and upper secondary school among boys and in upper school among girls. The relative risk of school injury compared with spare-time injury was 1.8 for boys and 2.6 for girls of compulsory school age. Most injuries occurred in sports area (boys: 34%, girls: 46%). The incidence of sports injuries showed no gender differences. The highest incidence rate was found in senior school girls. Twenty-five percent of all injuries were caused by other pupils, intentional violence being one important mechanism. Head injuries were more common among school injuries compared with spare-time injuries.     

Local anesthetics inhibit the G protein-mediated modulation of K+ and Ca++ currents in anterior pituitary cells

OBJECTIVES: To define the current causes and the optimal methods of early diagnosis and management of ureteric injuries, both iatrogenic (excluding endourologic) and traumatic, and to determine the outcome of these injuries and which identifiable factors affect this outcome. METHODS: A retrospective analysis was performed of all the 35 patients who sustained 40 ureteric injuries over a 5-year period (1991-1996). The methods used for diagnosis and management were reviewed. The outcome was assessed in terms of preservation of renal function. RESULTS: The study group was composed of 28 patients with 32 iatrogenic injuries and 7 patients with 8 injuries caused by external trauma. Gynecologic procedures accounted for 63% (20 of 32) of the iatrogenic injuries, whereas motor vehicle crashes accounted for 75% of the external injuries (6 of 8 injuries). The successful diagnostic rate for direct inspection (intraoperatively), intravenous urogram, retrograde pyelogram, and anterograde pyelogram were 33% for the former two and 100% for the latter two. Treatment consisted of primary open repair in 26 cases, a staged procedure in 7 cases, and endoscopic stenting in 5 cases. Of 36 cases with follow-up, complications developed in 9 cases (25%), 7 cases of which were corrected surgically. Overall incidence of nephrectomy was 8%, and the factors that seemed to affect the outcome adversely were pediatric age (< or =12 years), injury to upper ureter, delay in recognition, the presence of a urinoma, and/or associated organ injury. CONCLUSION: Iatrogenic trauma is the leading cause of ureteric injuries. The single controllable factor adversely affecting the outcome of this rather uncommon injury seems to be delayed diagnosis. Wound inspection and intravenous urogram are not reliable for early and accurate diagnosis, and a retrograde pyelogram or an anterograde pyelogram may be needed. Uncontrollable factors adversely affecting the outcome include young age, injury to upper ureter, and associated injuries all seen in association with external trauma rather than iatrogenic injuries.     

Tendon transfer for equinovarus deformed foot caused by cerebrovascular disease

Surgical correction was performed on 125 patients who had equinovarus deformity caused by a cerebrovascular accident and who needed an ankle foot orthosis for walking. The operative procedures involved anterior transfer of the long toe flexors (flexor hallux longus and flexor digitorum longus; long toe flexor group) or lateral transfer of the anterior tibial tendon (anterior tibial tendon group), combined with lengthening of the Achilles tendon. On evaluation more than 2 years after surgery, 83 of 110 patients of the long toe flexor group and eight of 15 patients of the anterior tibial tendon group were able to walk without a brace. Five patients of the anterior tibial tendon group who had shown strong contraction of the anterior tibial muscle during the swing phase before surgery, needed a brace because of a drop foot after surgery. Thus, lateral transfer of the anterior tibial tendon was abandoned in 1984. Recurrence of varus deformity was seen in approximately 15% of the patients in both groups. Anterior transfer of the long toe flexors, using them as dorsiflexor tendons or for tenodesis, seemed to produce better results.     

Case report: can sacroiliac joint dysfunction cause chronic Achilles tendinitis?

This case study discusses the possible relationship between chronic Achilles tendinitis and sacroiliac joint dysfunction. The patient presented is an active pole jumper, competing at both the national and international levels. He suffered from chronic Achilles tendinitis during the 1994-95 season, and conservative treatment applied locally was not successful. The athlete discarded the possibility of operative debridement of the tendon. Instead, an evaluation of the kinetic chain of the lower extremity and pelvic-lumbar area was performed, and the athlete was diagnosed with sacroiliac joint dysfunction and Achilles tendinitis. Evaluation findings, treatment program, and treatment outcome are also presented. The literature regarding sacroiliac joint mechanics and biomechanics of the foot-knee-hip and pelvic area is discussed and used to support the author's thesis that sacroiliac joint dysfunction, in this case a backward rotation of the right ilium, may have changed the kinematic chain of the lower extremity and caused a tendinitis in the Achilles tendon of the affected leg. Sacroiliac joint function and dysfunction, the reliability of sacroiliac joint mobility tests, and the validity of treatment programs are still considered controversial, and more research is needed to understand these mechanisms.     

Histopathological findings in chronic tendon disorders

Tendon injuries and other tendon disorders represent a common diagnostic and therapeutic challenge in sports medicine, resulting in chronic and long-lasting problems. Tissue degeneration is a common finding in many sports-related tendon complaints. In the great majority of spontaneous tendon ruptures, chronic degenerative changes are seen at the rupture site of the tendon (1). Systemic diseases and diseases specifically deteriorating the normal structure of the tendon (i.e. foreign bodies, and metabolic, inherited and infectious tendon diseases) are only rarely the cause of tendon pathology. Inherited diseases, such as various hereditary diseases with disturbed collagen metabolism and characteristic pathological structural alterations (Ehlers-Danlos syndrome, Marfani syndrome, homocystinuria (ochronosis)), represent approximately 1% of the causes of chronic tendon complaints (2), whereas foreign bodies are somewhat more common and are found in less than 10% of all chronic tendon problems (1). Rheumatoid arthritis and sarcoidosis are typical systemic diseases that cause chronic inflammation in tendon and peritendinous tissues. Altogether, these 'specific' disorders represented less than 2% of the pathological alterations found in the histological analysis of more than 1000 spontaneously ruptured tendons (1, 3, 4). In this material, degenerative changes were seen in a great majority of the tendons, indicating that a spontaneous tendon rupture is a typical clinical end-state manifestation of a degenerative process in the tendon tissue. The role of overuse in the pathogenesis of chronic tendon injuries and disorders is not completely understood. It has been speculated that when tendon is overused it becomes fatigued and loses its basal reparative ability, the repetitive microtraumatic processes thus overwhelming the ability of the tendon cells to repair the fiber damage. The intensive repetitive activity, which often is eccentric by nature, may lead to cumulative microtrauma which further weakens the collagen cross-linking, non-collagenous matrix, and vascular elements of the tendon. Overuse has also been speculated to cause chronic tendon problems, by disturbing the micro- and macrovasculature of the tendon and resulting in insufficiency in the local blood circulation. Decreased blood flow simultaneous with an increased activity may result in local tissue hypoxia, impaired nutrition and energy metabolism, and together these factors are likely to play an important role in the sequence of events leading to tendon degeneration (4). A sedentary lifestyle has been proposed as a main reason for poor basal circulation of the tendon, and presumably is at least partly responsible for the high number of tendon problems in people with a sedentary lifestyle who occasionally take part in high physical activity sports events.     

Methods and rationale for closed treatment of Achilles tendon ruptures

A method of closed treatment of Achilles tendon ruptures by casting, utilizing a long leg cast for 6 weeks and a short leg cast for 4 additional weeks, is presented. An experimental model using rabbits supports the clinical contention that closed approximation and immobilization of Achilles tendons allows tendon healing to progress, at least in the early stages. Observations made on the tendon sheath during early healing attribute a very positive role to it in providing needed blood supply to the tendon. The importance of maintaining a smooth gliding surface as well suggests that the tendon sheath should not be violated by surgical repair on the Achilles tendon.