Preoperative Deviation Research Articles

Augmented Asymmetric Lateral Rectus Recession in Intermittent Exotropia With Fixing Eye

Purpose: To document and compare the clinical results of symmetrical rectus muscle recession and asymmetrical rectus muscle recession in intermittent exotropia. Methods: The medical records of 27 patients who had symmetric bilateral rectus recession and 24 patients who had asymmetric bilateral rectus recession for intermittent exotropia with at least six months of postoperative follow-up from March 2004 to March 2007 were reviewed retrospectively. The authors performed a recession of 2 mm or greater in the deviating eye than in the fixing eye. Results: The mean age was 7.144.23 (range 3 to 15) years for symmetric bilateral rectus recession and 7.334.01 (range 3 to 14) years for asymmetric bilateral rectus recession. The mean follow-up was 11.835.74 (range 6 to 26) months in the symmetric bilateral rectus recession group and 11.145.05 (range 6 to 30) months in the asymmetric bilateral rectus recession group. The mean preoperative angle deviations were 27.54.8 prism diopter (PD) (range 30 to 40PD) and 27.34.6PD (range 20 to 40PD) in each group. The outcome of final follow-up (postoperative 24 months) was favorable in both groups, and slightly more successful in the asymmetric bilateral recession group but not a statistically significant amount (75.5% in the symmetric bilateral recession group and 81.2% in the asymmetric bilateral recession group). Conclusions: The present study suggests that there are no significant differences at postoperative 24 months between symmetric bilateral recession and asymmetric bilateral recession in intermittent exotropia having a fixing and a deviating eye.

Long-term results following osteotomy of the thumb delta phalanx in Rubinstein–Taybi Syndrome

Rubinstein-Taybi Syndrome is a rare condition affecting 1:125,000 children. It is associated with short broad radially deviated thumbs, secondary to a delta proximal phalanx of the thumb. We undertook a retrospective review of seven children (13 thumbs) with Rubinstein-Taybi syndrome whose thumbs were treated using a corrective osteotomy to the delta phalanx over a 13 year period. The types of osteotomy used in the series were reverse wedge osteotomy, opening wedge osteotomy and dome shaped osteotomy. The mean preoperative radial deviation of thumbs was 68 degrees (range 45-85 degrees ). At follow up five of the 13 thumbs demonstrated some residual radial deviation. All recurrences occurred in the dome shaped osteotomy group. Our data suggest that surgery is effective in correcting the deformity, but there is a risk of incomplete correction or recurrence. Despite the recurrence the mean postoperative deformity was significantly better than preoperatively and the majority of patients families subjectively reported good function. No patient in our series has yet undergone further corrective surgery.

Precaruncular approach for medial orbital wall periosteal anchoring of the globe in oculomotor nerve palsy

To evaluate a precaruncular approach for fixation of the globe to the medial orbital wall periosteum for management of complete third (oculomotor) nerve palsy. Consecutive patients with severe unilateral oculomotor nerve palsy present for at least 2 years were prospectively treated and evaluated. In all patients, a 12-16 mm recession of the lateral rectus muscle was performed along with the precaruncular anchoring procedure. Follow-up evaluations were performed at 1 week, and at 1, 2, and 3 months after surgery, with ongoing follow-up at 3 month intervals. Fourteen eyes of 14 patients with complete oculomotor nerve palsy were included in the series. The median horizontal preoperative deviation of -90(Delta) +/- 4.8(Delta) reduced to -10(Delta) +/- 8.3(Delta). The vertical deviation reduced from 24(Delta) +/- 7.4(Delta) to 12.8(Delta) +/- 6.0(Delta). Mean follow-up was 8.9 +/- 5.5 months (range, 6-21 months). A slight exotropic drift was observed over 4 to 6 weeks following surgery in all cases. Satisfactory alignment was observed in 13 of the 14 cases (92.85%) over the duration of the follow-up period. Anchoring the globe to the medial orbital wall using a precaruncular approach is a viable option in the management of complete external oculomotor nerve palsy.

Superior oblique tucking with versus without additional inferior oblique recession for acquired trochlear nerve palsy

Inferior oblique recession (IOR), superior oblique tucking or advancement (SOT) and a combination of both (SOT&IOR) are most popular as treatments for acquired trochlear nerve (N.IV) palsy. Recently, it has been reported that results of a modified SOT technique and SOT&IOR were nearly equivalent. We investigated the effects of SOT and SOT&IOR in 37 patients with unilateral acquired isolated N.IV palsy. Retrospective study of patients with unilateral acquired N.IV palsy who were operated at the University Hospitals of Giessen (1996 to 2007) and Essen (2003 to 2007). Examinations with Harms' tangent scale (2.5 m, dark red glass in front of non-paretic eye) were performed before and 3 months after pure SOT or SOT + IOR. When the palsy was on OS, squint angles were transformed corresponding to palsy on OD. horizontal, vertical and cyclotorsional deviations in nine diagnostic gaze directions and the field of binocular fusion. In total, it was possible to examine 37 patients 3 months post surgery: 16 had received pure SOT, and 21 SOT&IOR. Preoperative deviations did not differ significantly between the pure SOT and SOT&IOR groups. Dosage was 6 to 8 mm for pure SOT (median, 8) and 8 to 18 mm (median, 11) for SOT&IOR (with 4 to 8 mm SOT). At 3 months, elevation deficiency in adduction was less severe with pure SOT compared to SOT&IOR, but at the same time the effect on the vertical deviation was less pronounced. Additional IOR augments the effect of SOT, but also its side-effects, i.e. consecutive Brown's syndrome.

Effect of 10-mm Superior Oblique Posterior Tenectomy Combined with Frenulum Dissection in A-Pattern with Superior Oblique Overaction

To evaluate the effect of 10-mm tenectomy of the posterior fibers of the superior oblique (SO) tendon combined with dissection of the frenulum for correction of A-pattern deviation and vertical deviation with SO overaction. Retrospective, interventional case series. Seventy-five patients with A-pattern strabismus associated with SO overaction who underwent surgery between March 1, 2004 and August 31, 2007. Retrospective analysis of A-pattern strabismus patients with SO overaction who underwent unilateral or bilateral 10-mm SO posterior tenectomy combined with frenulum dissection and who underwent at least 12 months of follow-up. The mean preoperative amount of A-pattern for all patients was 21.20 +/- 7.25 prism diopters (PD), with a mean postoperative collapse of 17.63 +/- 5.33 PD (range, 10 to 30 PD), which was statistically significant (P = .001). After surgery, the mean A-pattern correction was 22.12 +/- 6.30 PD in the group that underwent bilateral posterior tenectomy and 13.33 +/- 5.20 PD in the group that underwent unilateral posterior tenectomy. The mean degree of preoperative vertical deviation in the group that underwent unilateral posterior tenectomy was 11.50 +/- 3.96 PD, and the mean correction was 9.21 +/- 4.22 PD (P = .01). There were no surgical complications, except in 5 patients, who manifested mild inferior oblique overaction. We believe that 10-mm SO posterior tenectomy combined with frenulum dissection effectively collapses A-pattern deviation of less than 25 PD with mild to moderate SO overaction and reduces associated vertical deviation of 10 PD.

Correction of post-traumatic lower limb deformities using the Taylor spatial frame

Twenty-five post-traumatic leg length discrepancies combined with axial deviation in 22 patients were treated with the Taylor spatial frame. We retrospectively analysed the accuracy of correction, the complication rate and the clinical outcome including the duration of treatment. The cases were divided into three sub-groups according to the level of the osteotomy. The mean age at operation was 22.7 years; the mean follow-up was 21.1 months. The patients presented uniplanar and multiplanar deformities in combination with leg length discrepancy. Twenty-one of 25 cases showed a frontal plane malalignment preoperatively. Only three of those 21 cases continued to show minimal malalignment postoperatively. The preoperative mechanical axis deviation present in 15 of 17 lower extremities was fully corrected in 13 extremities. The 25 lengthening and correction procedures were associated with a total of 61 difficulties, including 44 problems, seven obstacles and ten complications. In conclusion, the Taylor spatial frame allows accurate results in correction of complex post-traumatic deformities with minimal morbidity.

Bilateral lateral rectus recession considering the tendon width in intermittent exotropia

The tendon width of the lateral rectus muscle can be a useful indicator of the effect of unilateral lateral rectus recession in intermittent exotropia. The aim of this study was to determine whether the tendon width of lateral rectus would be useful for predicting the effect of bilateral lateral rectus (BLR) recession. We studied a total of 45 patients between 3 and 15 years of age who had undergone bilateral rectus recession for the basic type of intermittent exotropia. The actual effect of lateral recession was calculated by adding the absolute value of the angle of preoperative deviation and the postoperative deviation on the second day and dividing the figure by the total amount of recession. We then calculated the hypothetical effect of lateral rectus recession, considering the tendon width of each eye, and added the effects of both eyes. The hypothetical effects were defined as 3 PD when the tendon width was 8-8.5 mm; 3.5 PD when it was 7-7.5 mm; and 2.5 PD when it was 9-9.5 mm, based upon earlier statistical analysis. We compared both effects using a paired t-test. The mean difference between the actual and the hypothetical effects of BLR recession in all patients was 2.88 PD (P=0.001, range: 0-5.50 PD). However, when the amount of preoperative exodeviation was below 25 PD, the differences were not statistically significant (P=0.086). The tendon width may also be useful indicator in BLR recession if the preoperative exodeviation is below 25 PD.

Results of Monocular Surgery Under Peribulbar Anesthesia for Large-Angle Horizontal Strabismus

OBJECTIVE:To evaluate the results of monocular surgery under peribulbar anesthesia for large-angle horizontal strabismus.INTRODUCTION:Monocular surgery may preserve some muscles if a repeat operation is required, may help to avoid the exposure of the dominant eye to the inherent risks of a surgical procedure and may reduce surgical time.METHODS:We evaluated ninety-two consecutive patients who underwent monocular surgery under peribulbar anesthesia for large-angle horizontal strabismus (angle of 40 prism diopters or greater). Patients were divided into group 1- esotropia and group 2 –exotropia. The postoperative follow-up was at 6 months, when the residual deviation was evaluated. In cases of residual deviations of over 15 PD (prism diopter), a second procedure was indicated.RESULTS:In all patients with preoperative deviations up to 60 PD, residual deviations were under 15 PD. Some patients with preoperative deviations of 65 PD (two in group 1 and four in group 2) and all patients with deviations over 65 PD had residual deviations over 15 PD. The 13 patients who underwent a second procedure experienced successful outcomes. Our ROC curve analysis showed that the cutoff point for obtaining a successful surgical result was 62.5 PD. No patient presented with a major limitation in respect of ocular movement.CONCLUSIONS:Monocular surgery under peribulbar anesthesia can be an alternative for horizontal large-angle strabismus given deviations of up to 60 PD. Monocular surgery did not result in successful outcomes for deviations of over 65 PD.

Transposition gerader Augenmuskeln zur Behandlung komplexer Motilitätsstörungen

Transposition techniques alter the muscle paths thereby creating new directions of muscle force. Extraocular muscle transposition procedures have been used to treat abducens palsy, Duane's retraction syndrome, double-elevator palsy and other complex ocular motility abnormalities. The purpose of this study was to evaluate the surgical and functional results of rectus muscle transposition in patients with different aetiologies of severe ocular motility deficits. Between 1992 and 2008 rectus muscle transposition surgery has been performed on 31 patients. In this retrospective case series one patient with an abducens nerve palsy is presented as an example. In addition, six patients with motility disorders of different aetiologies who had transposition manoeuvers were evaluated. Preoperative, surgical and postoperative data are reported. Rectus muscle transposition has been performed because of severe functional loss of the lateral rectus muscle, the superior rectus muscle or the medial rectus muscle as well as in myopic strabismus fixus. One of the patients had traumatic sixth nerve palsy. The underlying pathology in patients who had superior transposition of the horizontal rectus muscles were double-elevator palsy, congenital oculomotor nerve palsy and hypotropia caused by sphenoid wing hypoplasia. A nasal transposition of the vertical rectus muscles was performed in traumatic and tumour-associated muscle loss of the medial rectus muscle. The large preoperative deviations were markedly reduced postoperatively and even ocular motility partially improved. Transposition surgery seems to be a suitable procedure for the treatment of complex ocular motility disorders. In cases of a complete lack of function of an extraocular muscle or in complex, uncommon conditions, which are difficult to treat with any other surgery, muscle transposition seems to be an effective procedure.

LASIK and PRK in Refractive Accommodative Esotropia: A Retrospective Study on 20 Adolescent and Adult Patients

To evaluate the clinical results obtained with excimer laser treatment of fully refractive accommodative esotropia. Fully refractive accommodative esotropia was corrected in 17 patients with laser in situ keratomileusis (LASIK) and in 3 patients with photorefractive keratectomy (PRK). The mean age of the patients at time of refractive surgery was 18.8 years (range 14 to 24 years). All surgical procedures were performed under local anesthesia. The preoperative and postoperative data were retrospectively analyzed with regards to visual acuity, ocular alignment, and stereopsis. The mean preoperative deviation without correction was 18.1Delta for near vision and 13.7Delta for distance vision. After refractive surgery the mean postoperative deviation was 4Delta esophoria at near, and 2.5Delta of esophoria at distance: 10 patients (50%) showed esophoria for both distance and near vision, 2 patients (10%) esophoria only for near vision, and 8 patients (40%) orthophoria for both distance and near vision. Emmetropia (-/+1.00 D) was obtained in 97.5% of eyes (39 of 40). The mean correction obtained with excimer laser was +4.62 D(range +2.25 to +7.75, SD 4.52). The preoperative BSCVA was in all eyes greater than or equal to 20/30. There were no significant differences observed between the preoperative and postoperative mean best-corrected visual acuity (p=0.32). There were no complications. The follow-up period lasted a mean of 30.2 months. The treatment of fully refractive accommodative esotropia with excimer laser was found effective and safe, even in young or adolescent patients. More studies are needed to increase the patient experience and extend the follow-up period in order to evaluate the stability of these results over time.

Cerebral Protection by Lidocaine During Cardiac Operations: A Follow-Up Study

A previous study showed less postoperative neurocognitive impairment in open-chamber cardiac surgery patients given lidocaine for 48 hours after induction of anesthesia. In the present study, we aimed to test the benefit of a 12-hour infusion in a broader group of cardiac surgery patients, including those undergoing coronary artery bypass graft surgery. This was a randomized, double-blind, intention-to-treat trial. Before cardiac surgery, 158 patients completed 7 neurocognitive tests and a self-rating scale for memory. They received a 12-hour infusion of either lidocaine in a standard antiarrhythmic dose or placebo, beginning at induction of anesthesia. The cognitive tests and memory scale were repeated at postoperative weeks 10 and 25. A deficit in any cognitive test was defined as a decline in score by more than or equal to the preoperative group standard deviation. All tests were completed by 118 and 107 patients at 10 and 25 weeks, respectively. The proportions of patients in the lidocaine and placebo groups exhibiting a deficit in one or more tests were as follows: 45.8% versus 40.7% at 10 weeks, and 35.2% versus 37.7% at 25 weeks (not significant). There were no significant differences between groups in self-ratings of memory function or length of intensive care unit or hospital stay. Lidocaine was not neuroprotective. The result of the previous trial may represent a type 1 error. Alternatively, benefit may be more likely for open-chamber surgery patients exposed to larger numbers of emboli or with a longer lidocaine infusion.

Minimally invasive strabismus surgery (MISS) for rectus muscle transpositions

Aims:To present two similar, minimally invasive strabismus surgery (MISS) techniques for rectus muscle transpositions.Methods:The technique and results of 10 consecutive MISS muscle transpositions performed in eight patients by applying only...

130: Managing Graves orbitopathy: Honing your skills to improve outcome

This workshop provides a practical approach to the management of Graves' orbitopathy with emphasis on the associated restrictive strabismus. Patient selection, timing of strabismus surgery vis-a-vis associated orbital or eyelid surgery, and medical management, including advances in immune modulators, corticosteroids, and radiation therapy, will be covered. A how-to description of surgery designed to resolve or equalize relative intereye restrictive strabismus covers the correlation between preoperative deviation, findings on forced ductions, and amount of surgical recession.

Comparison of the Stability of Postoperative Alignment in Sensory Exotropia: Adjustable Versus Non-Adjustable Surgery

PurposeTo compare the success rates and stabilities of postoperative alignment between adjustable and the non-adjustable surgeries in the treatment of sensory exotropia.MethodsA retrospective analysis was performed on all patients with sensory exotropia who had undergone unilateral lateral rectus recession and medial rectus resection (R&R) between January 1998 and August 2005. Thirty-four patients underwent conventional R&R, and 20 patients underwent R&R with adjustable suture of the lateral rectus. The surgical results between the two groups were analyzed with regard to the preoperative and post-operative deviation angles and the postoperative drift. The postoperative deviation angle was measured on postoperative day 1 as well as at two weeks, three months, six months and the final visit after surgery.ResultsThere were no statistically significant differences in the mean preoperative and postoperative deviation angles between the two groups. In 30 (88%) patients in the non-adjustable group and 15 (75%) patients in the adjustable group, postoperative deviation was less than 15 prism diopters (PD) at the three month follow-up. There was no significant difference in the mean postoperative drift between the two groups.ConclusionsStrabismus surgery with adjustable sutures did not show a significantly better result than surgery without adjustable sutures in the treatment of sensory exotropia. Considering the amount of postoperative exodrift in both groups, we postulate that the immediate ocular alignment after surgery for sensory exotropia should be orthophoric or 5-6 PD of esodeviation.

Fixator-Assisted Acute Femoral Deformity Correction and Consecutive Lengthening Over an Intramedullary Nail

External fixators are being used frequently in standard limb-lengthening and deformity-correction procedures. Lengthening over an intramedullary nail has been a successful technique, and fixator-assisted intramedullary nailing has provided satisfactory results for the correction of selected deformities. We report a combined technique for the treatment of femoral deformities associated with shortening. Between 1997 and 2005, twenty-eight femora in twenty-five patients with a median age of twenty-seven years underwent reconstruction with an intramedullary nail and a unilateral fixator. The mean amount of shortening was 6.33 cm, and the mean preoperative mechanical axis deviation was 33.86 mm. Deformity correction was performed acutely and secured by the intramedullary nail, which was locked distally, and the same external fixator that was used for the deformity correction was utilized for lengthening. At the end of the distraction period, proximal locking screws were placed in the intramedullary nail and the external fixator was removed. At the time of follow-up, deformity correction and bone healing were assessed clinically and radiographically, complications were noted, and the functional results were assessed. The mean duration of follow-up was forty months. The mean duration of the external fixation was 83.29 days, and the mean external fixation index was 14.98 days/cm. The mean amount of lengthening was 6.02 cm. The mean amount of mechanical axis deviation at the end of the treatment was 11.29 mm. The mean bone healing index was 36.66 days/cm. A knee flexion contracture developed in one patient and resolved after intensive rehabilitation. One patient underwent two revisions because of Schanz screw displacement secondary to cortical fracture, and four patients with minor pin-track infections were treated successfully with local wound care and oral antibiotics. While femoral lengthening and deformity correction can be obtained with classic methods for application of an external fixator, the long period of external fixation, patient discomfort, and plastic deformation of the regenerated bone after removal of the fixator are major disadvantages. Two techniques, fixator-assisted nailing and lengthening over an intramedullary nail, were combined in this series. The duration of the external fixation was reduced compared with that required for classic treatment with an external fixator and patient comfort was increased. In addition, the intramedullary nail prevented fracture and deformation of the regenerated bone.

The Effect of Medial Rectus Resection in Reccurent Exotropia After Lateral Rectus Recession

Purpose: To investigate the effect of unilateral medial rectus resection in recurrent exotropia under 25 Prism Diopter after unilateral or bilateral lateral rectus recession. Methods: A retrospective chart analysis was conducted for 21 patients who underwent unilateral medial rectus resection for recurrent exotropia under 25PD and uni- or bilateral lateral rectus recession for prior surgery of exotropia. The medial rectus was resected from 5.0 to 7.0 mm by 0.5 mm according to angle deviation at a distance. The postoperative deviated angle was checked at one week, three months and six months postoperatively to investigate the amount of corrected deviation per resected muscle. Results: The average preoperative deviation was 20.573.37PD. We resected mean 6.10.62 mm of the medial rectus. At one week after the surgery, the postoperative deviated angle was 2.004.32PD, After six months it was 6.577.40PD, and there appeared to be an increase of deviation. Ten patients (48%) fused before surgery and 12 (57%) after surgery. The corrected deviation per resected muscle was 2.881.08PD. Conclusions: Unilateral medial rectus resection is an effective surgical method for the treatment of recurrent exotropia under 25 PD after lateral rectus recession.

Recurrence of Intermittent Exotropia: Factors Associated with Surgical Outcomes

Introduction: The surgery of choice for intermittent exotropia (XT) continues to be debated, with little evidence that one procedure provides a more successful outcome than the other in the longer term. Many factors, however, may potentially influence the outcome of strabismus surgery for intermittent XT. This study aimed to investigate factors associated with the recurrence of an exo-deviation following horizontal muscle surgery for intermittent XT of the divergence excess type. Methods: We retrospectively reviewed the medical histories of patients who underwent surgery for the correction of intermittent XT between January 1998 and June 2005. The factors analyzed were as follows: sex, age of onset, age at initial surgery, family history, size of preoperative deviation, near binocular single vision, amblyopia, oblique dysfunction, refractive error, type of surgery, and postoperative alignment. Results: Eighty-nine patients were included in the final analysis. Of these, 19 demonstrated recurrence of their deviation. The mean follow-up period was 2 years. None of the factors analysed appeared to influence the outcome of intermittent XT surgery. Conclusion: We found that no single factor influenced patients' responses to the surgical treatment of intermittent XT. To address controversies and improve the evidence base regarding surgical intervention of this condition, randomized controlled trials are needed and justified because the results indicate that it would be relatively safe to randomly allocate patients to groups who could receive differing treatments so as to determine optimum management strategies.

Bilateral Medial Rectus Recession Posterior to the Functional Equator in Esotropia Over 40 Prism Diopters

Purpose: To investigate bilateral medial rectus recession by considering functional equator as a surgical guideline in esotropia over 40 prism diopters (PD). Methods: Forty-one patients who underwent bilateral medial rectus recession, and were followed-up for more than 12 months, were reviewed. The success rate was compared between group 1 and group 2, which were divided to recession site from the functional equator posterior, and also between the hyperopia group and myopia group according to refraction. Results: According to preoperative deviation angle, 21 patients underwent recession to less than 10 mm posterior to the functional equator (group 1) and 20 patients had recession to 1.5 mm to 2.0 mm posterior to the functional equator (group 2). No significant difference in success rate between group 1 (71.4%) and group 2 (75.0%) was detected at the last follow-up. When divided into a hyperopia group (26 patients) and myopia group (15 patients), the success rate in the myopia group was higher than in the hyperopia group, as observed at the last follow-up, but the difference was not significant. There was 1 case of overcorrection in each group. Conclusions: A successful outcome was achieved in 30 patients (73.2%), and overcorrection in 2 patients (4.9%) when recessed to 2.0 mm posterior to functional posterior in esotropia over 40PD.

Minimally invasive strabismus surgery for horizontal rectus muscle reoperations

Aims:To study if minimally invasive strabismus surgery (MISS) is suitable for rectus muscle reoperations.Methods:The study presents a series of consecutive patients operated on by the same surgeon at Kantonsspital St...

Value of alignment osteotomy of the proximal tibia in the endoprosthesis period

To evaluate the value of high tibial osteotomy in times of growing numbers of endoprostheses we compared our personal with other results of this method as well as of the unilateral sledge prosthesis. Between 1972 and 1993 the high tibial osteotomy as described by Coventry was performed in 105 patients. 98 patients could be examined clinically-radiologically and evaluated with a questionnaire. The indication for surgery was given in patients with unilateral arthrosis without affection of the retropatellar joint and without significant ligamentous instability. The varus deviation was in no case more than 10 degrees. The average follow-up for the clinical-radiologic examination was 9.4 years. 77 patients (78.6%) were satisfied with the outcome of the surgery. Here it was seen that neither age nor pain or instability had an influence on this judgement. The walking distance on the other hand had a significant influence. Stair climbing and range of motion were significantly important as well. 23 patients gave the judgement "excellent", 31 "good", 36 "satisfactory" and 8 patients were "not satisfied". A significant influence of patient age on the judgement could not be proven. The division in the Japanese Score showed "good" results in 14%, "moderate" in 81% and "poor" in 5%. 13 knee joints (13.3%) were absolutely pain-free and in 67 cases (68.4%) there were a definite pain reduction. A significant correlation between the preoperative axis deviation and pain could not be found. An average flexion of 97.5 degree and an extension deficit of 3.3 degree on average was seen. A significant difference of range of motion dependent on age groups could not be found. In 42 knees (42.9%) the lateral ligaments were clinically stable, in 35 cases (35.7%) there was a first degree lateral stress gap and in 21 cases (21.4%) there was a second degree lateral instability. A significant correlation between the instability and age or pain could not be proven. 13 revision surgeries including 9 endoprosthesis implantations were performed. The study showed a high level of satisfaction with an exact surgical indication. When seeing the growing number of implanted uni- or tricompartmental endoprostheses the procedure of tibial osteotomy can be suggested for patients with unilateral arthrosis without retropatellar arthrosis, with an axis deviation less than 15 degrees, with unaffected cartilage of the contralateral compartment and without ligamentous insufficiency independent of patient age.